Introduction

Millet and rice were domesticated approximately 10,000 years ago in northern and southern China, respectively1,2,3,4. Following their domestication, millet and rice agriculture dispersed to the south and north, likely facilitated by population migration, cultural interactions, and environmental adaptation5,6,7. The north-south transitional zone of China8, characterized by high environmental complexity, biodiversity, and a transitional climate9, played a crucial role in facilitating the movement of people and the exchange of agricultural technologies. Archaeobotanical evidence indicates a mixed agricultural system combining millet and rice cultivation developed in this transitional zone6,10,11,12,13. Three primary crop dispersal routes have been proposed for Neolithic China: the west corridor (Gansu-Qinghai to Chengdu Plain), the central corridor (Central Plains and Hanshui River region), and the east corridor (Haidai to Jiangsu-Zhejiang regions)6. Among these, the central corridor, particularly the middle Hanshui River region, is notable for its early and frequent crop exchanges in prehistoric and historic times. (By ‘middle Hanshui River region,’ we refer to the middle reach of the Hanshui River, the largest tributary of the Yangtze River).

Several sites in the middle Hanshui River region, including Baligang, Gouwan, Shenmingpu, Wenkandong, Wuying, Dasi, Xiawanggang, Qinglongquan, Jijiawan, Mulintou, and Xiajiangjiabianzi, have been excavated and studied for their plant macro-remains (see Fig. 1 for geographic locations of the above sites and Supplementary Tables 1–4 in Supplementary Information for their plant macro-remains results). These studies reveal that millet-rice mixed agriculture was established at Baligang around 8400 years ago and persisted in subsequent periods14. The western mountainous areas are predominantly millet-based, while the eastern plains are dominated by rice farming15.

Fig. 1: Maps showing the study area and geographic locations of the sites mentioned in text.
figure 1

a The study area. b Geographic locations of sites where archaeobotanical studies have been conducted (1, Baligang; 2, Gouwan; 3, Wuying; 4, Xiawanggang ; 5, Wenkandong; 6, Shenmingpu; 7, Qinglongquan; 8, Dasi; 9, Jijiawan; 10, Mulintou; 11, Xiajiangjiabianzi; and 12, Fenghuangzui).

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The recent discovery of a Late Neolithic earthen-walled town at Fenghuangzui in Xiangyang City, Hubei Province, provides new insights into the agricultural patterns of the middle Hanshui River region. Influenced by the Qujialing and Shijiahe cultures from the Jianghan Plain, Fenghuangzui shows less influence from the Central Plains despite its geographic proximity to the Central Plains16. To understand the subsistence strategies of Fenghuangzui’s inhabitants and their differences from those in the western or northern Hanshui River region, we conducted an archaeobotanical study of plant macro-remains from the site. Our findings reveal the agricultural foundation of the Fenghuangzui walled town and contribute to a more comprehensive understanding of agricultural structures in the middle Hanshui River region during the Qujialing to Meishan periods.

Methods

The middle Hanshui River region, a transitional zone between North and South China, encompasses three geomorphological areas: western mountains, northern basins, and southern plains (see Fig. 1b). It serves as a cultural meeting point between the Central Plains and the Jianghan Plain, with shifting cultural influence over time. Key cultures in the region include the Yangshao (7000—5000 cal BP), Qujialing (5300–4500 cal BP), Shijiahe (4500–4200 cal BP), and Meishan (4200–3900 cal BP) cultures17.

The Yangshao culture, originating in the Yellow River Basin, is known for its painted pottery18 and dry farming of foxtail millet (Setaria italica) and broomcorn millet (Panicum miliaceum). The Qujialing culture, centered in the Jianghan Plain of the middle Yangtze River region, featured large settlements with fine-paste black and gray pottery, including bei-cups, wan-bowls, hu-jars, and dou-stemmed bowls19. The surfaces of the pottery are predominantly plain, though a small portion features decorations such as string patterns, basket patterns, incised patterns, and appliqué patterns20. The Shijiahe culture, originating in the Jianghan Plain, is marked by gray and black pottery, ritual animal figurines, advanced jade production, and evidence of social stratification19,21. The Meishan culture, emerging in the Central Plains of the Yellow River, produced high-fired, thin-walled black and gray pottery, including guan-jars, ding-tripods, and pan-basins22.

The Fenghuangzui site (32°14′42.67″ N, 111°59′20.39″ E) (Fig. 1b), a 15-ha Neolithic walled settlement in Xiangyang City, Hubei Province, was occupied during the Qujialing, Shijiahe, and Meishan periods (see Table 1). Excavation since 2020 reveals a nearly square-shaped town with moats and river courses23,24. Pottery styles are strongly influenced by the Jianghan Plains, despite its proximity to the Central Plains16. Paleoenvironmental studies25 indicate a warm, humid climate during the Qujialing period, supporting cultural expansion. Cooling and drying during the Shijiahe period led to the site’s decline from a regional center to an ordinary settlement. By the Meishan period, the strong influence of the Central Plains was evident at the site, probably leading to the site’s abandonment. These broader paleoenvironmental conditions align closely with the rise and decline of the town, as evidenced by the archeological record.

Table 1 AMS 14C dating results of charcoal samples (cited from ref. 23)
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Flotation and identification of plant macro-remains

The present study aims to understand the agricultural foundation of the Fenghuangzui walled town during the Neolithic times and its potential changes over time, from the perspective of plant macro-remains. Archaeological plant remains are broadly categorized into macro-remains (visible to the naked eye, e.g., seeds, wood) and micro-remains (requiring microscopy, e.g., pollen, phytoliths, starch grains)26. Flotation, a well-established method for recovering plant macro-remains26,27, has been widely applied in Chinese archeology since the 2000s28. We employed the flotation method for plant macro-remains recovery. Adopting a sampling strategy developed by Zhijun Zhao, a prominent Chinese archaeobotanist29, we collected 418 soil samples (~10 L each, totaling 4916 L) from various features and contexts dating to the Qujialing to Meishan periods, including ash pits, house structures, ash ditches, stratigraphic units, and so on (see archeological contexts of the selected soil samples in Table 2). A simple bucket flotation method was used, with light fractions collected on a 0.2 mm mesh. Soil samples were manually agitated and soaked to enhance recovery. Shade-dried samples were analyzed at Wuhan University’s Archeology Department, where charred remains (charcoal, seeds, and fruits) were identified using published references and examined under an Olympus SZX7 microscope. Uncharred materials were excluded as modern intrusions. Data were analyzed using absolute counts, density, proportions, and ubiquity to assess seed/grain abundance and distribution. Spatial patterns were visualized using ESRI’s ArcMap 10.1, identifying hotspots and coldspots of seed/grain distribution and potential intra-community differences in food consumption within the community. This approach provides insights into the agricultural and subsistence strategies of Fenghuangzui’s Neolithic inhabitants over time.

Table 2 Archeological contexts for soil samples selected for flotation
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Results

Charcoals are black, carbon-rich material produced by heating plant materials in an environment with limited oxygen. This incomplete combustion removes water, volatile compounds, and other organic components, leaving behind a lightweight, porous, and carbon-dense residue. Charcoal remains, derived from human use of wood for fuel and raw materials, serve as valuable archaeobotanical evidence for reconstructing long-term anthropogenic landscapes30. In this study, only charcoal fragments larger than 1 mm were weighted, totaling 152.78 g, with an average content of 0.03 g/L. A total of 2942 charred plant seeds were recovered, of which 2782 were identified to the species level. The remaining 160 seeds, severely damaged or lacking diagnostic features, were classified as ‘unknown’ (Table 3). The identified seeds represent 28 species across 14 families, categorized into two groups: crop seeds and non-crop seeds. This dataset provides insights into agricultural practices and the broader use of plant resources.

Table 3 Flotation results of plant macro-remains at the Fenghuangzui site
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Four major crops

Four crops were identified from the charred grains: rice (Oryza sativa), foxtail millet (S. italica), broomcorn millet (P. miliaceum), and wheat (Triticum aestivum) (Fig. 2). These totaled 2526 grains, representing 90.83% of the identifiable charred plant seeds.

Fig. 2: Carbonized crop grains from the Fenghuangzui site.
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a O. sativa. b S. italica. c P. miliaceum. d T. aestivum.

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(1) Rice (O. sativa): a total of 2504 charred rice grains were recovered, accounting for 99.13% of the crop grains, with a ubiquity of 62.9%. The grains were well-preserved, exhibiting an elongated ellipsoid shape with two surface notches (Fig. 2a). Measurements of 20 grains yielded average dimensions of 4.8 mm (length), 2.46 mm (width), and 1.99 mm (thickness), with a length-to-width (L/W) ratio of 1.95. We infer that the rice found at Fenghuangzui belongs to the japonica subspecies (O. sativa ssp. japonica), as this subspecies typically has an L/M ratio of less than 2.231.

(2) Foxtail millet (S. italica): fourteen charred foxtail millet grains were identified, representing 0.55% of the crop grains, with a ubiquity of 3.1%. The grains are subglobose, with a bulging globular abdomen and a “U”-shaped embryonic region (Fig. 2b). Size variations suggest mature (A-type) and immature (C-type) grains, with mature grains exclusively found in the Shijiahe cultural contexts32.

(3) Broomcorn millet (P. miliaceum): three charred broomcorn millet grains were recovered, accounting for 0.12% of the crop grains, with a ubiquity of 0.72%. The grains are subglobose, with a rough surface and a “V”-shaped embryonic region (Fig. 2c). Two well-preserved grains averaged 1.67 mm (length) and 1.57 mm (width).

(4) Wheat (T. aestivum): five charred wheat grains were identified, representing 0.2% of the crop grains, with a ubiquity of 0.96%. The grains are ovate-ellipsoid, with a raised dorsal surface and pronounced ventral grooves (Fig. 2d). Two grains averaged 3.08 mm (length), 1.91 mm (width), and 1.54 mm (thickness). One grain was collected from the Qujialing (5300–4500 cal BP) context, and the other four from the Shijiahe (4500–4200 cal BP) context. These findings are among the earliest wheat remains in the middle Hanshui River region33, though accelerator mass spectrometry (AMS) 14C dating is needed to confirm this inference.

Next, we described crop remains by cultural periods (Qujialing, Shijiahe, and Meishan) (Fig. 3). In the Qujialing period, of 684 identifiable charred seeds, 618 (90.35%) were crop grains, including 612 (99.03%, ubiquity 69.92%) rice gains, four foxtail millet grains (0.65%, ubiquity 3.01%), one broomcorn millet grain (0.16%, ubiquity 0.75%), and one wheat grain (0.16%, ubiquity 0.75%) (Fig. 3). Rice dominated the diet, while millets and wheat were negligible. In the Shijiahe period, of 2032 identifiable charred seeds, 1856 (91.34%) were crop grains, including 1840 rice grains (99.14%, ubiquity 56.91%), ten foxtail millet grains (0.54%, ubiquity 3.66%), two broomcorn millet grains (0.11%, ubiquity 0.81%), and four wheat grains (0.22%, ubiquity 1.22%) (Fig. 3). Rice remained predominant, with minimal contributions from millets and wheat. In the Meishan period, all 52 grains recovered were rice, accounting for 78.79% of the charred seeds, with a ubiquity of 48.72% (Fig. 3). No millets or wheat were found, indicating rice was the sole cultivated crop during this period.

Fig. 3
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Percentage and ubiquity of crops in each period (Qujialing, Shijiahe, and Meishan) at the Fenghuangzui site.

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From the Qujialing to Meishan periods, rice was the dominant crop at Fenghuangzui, becoming the sole cultivated crop by the Meishan period. Foxtail millet, broomcorn millet, and wheat were present in small quantities during the Qujialing and Shijiahe periods, suggesting minimal dry farming. These findings highlight the centrality of rice farming in supporting Late Neolithic town life at Fenghuangzui, with dry farming playing a minor role.

The number of charred seeds varies significantly across periods (Table 3), primarily due to differences in the volume of soil samples collected, which reflects the abundance of cultural deposits in each period. To reduce the sampling bias, we standardized the data and used percentages and ubiquity in the discussion section.

Non-crop seeds

A total of 256 seeds, representing 14 families, were recovered through flotation analysis, accounting for 9.37% of the identifiable plant seeds (Fig. 4). The most abundant were Chenopodiaceae (75 seeds, 29.3% of non-crop seeds), followed by Portulaca oleracea (47 seeds, 18.36% of non-crop seeds) and Acalypha australis (25 seeds, 9.77% of non-crop seeds). These findings highlight the diversity of wild plant resources utilized at the site.

Fig. 4: Carbonized non-crop seeds at the Fenghuangzui site.
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a C. album. b P. oleracea. c A. retroflexus. d S. juncoides. e G. soja. f S. viridis. g P. aviculare. h P. lapathifolium. i Galium. j Oxalis corniculata. k S.chinensis.

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Discussion

The middle Hanshui River region, home to the Fenghuangzui site, is a crucial zone for crop exchange and population movement between North and South China. By analyzing crop structures at Fenghuangzui and integrating data from other sites in the region (see Fig. 5), we observe significant spatio-temporal changes influenced by geography, cultural evolution, and climate variability.

Fig. 5: Bar chart of the percentage and ubiquity of crops in different periods in the middle Hanshui River region.
figure 5

a and b Yangshao period. c and d Qujialing period. e and f Shijiahe period. g and h Meishan period.

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Yangshao period (7000–5000 cal BP)

No plant remains were recovered from Fenghuangzui during this period. However, studies at four other sites— Baligang (northern basins) and Gouwan, Dasi, and Xiawanggang (western mountains)—revealed a mixed agricultural system of millet and rice (Fig. 5a, b). Rice dominated in the northern basins, while millet farming prevailed in the western mountains, reflecting geomorphological influences: flat northern basins facilitated rice irrigation, whereas mountainous terrain favored drought-tolerant millet.

Qujialing period (5300–4500 cal BP)

Plant macro-remains from seven sites, including Fenghuangzui, Baligang, and Qinglongquan, indicate a continuation of mixed dry-rice agriculture, with a significant increase in rice cultivation (Fig. 5c, d). The Qujialing culture, originating in the Jianghan Plain, expanded northward, establishing rice farming as its agricultural foundation. Fenghuangzui, located in the southern Xiangyang-Yicheng Plain, exhibited the most intensive rice cultivation, closely resembling the Jianghan Plain’s agricultural structure34. Cultural connections are further supported by similarities in pottery types between Fenghuangzui and Zoumaling sites in the Jianghan Plain16,35.

Shijiahe period (4500–4200 cal BP)

Analysis of plant macro-remains from Qinglongquan, Gouwan, Xiawanggang, Baligang, and Fenghuangzui, shows the persistence of mixed dry-rice agriculture (Fig. 5e, f), with advancements in dry farming. Wheat appeared at some sites but remained insignificant. Agricultural patterns established during the Qujialing period continued, with rice cultivation thriving in the southern plains and mixed farming in the western mountains and northern basins.

Meishan period (4200–3900 cal BP)

Data from seven sites, including Fenghuangzui, Wenkandong, and Baligang, reveal a shift toward dry agriculture, with reduced rice cultivation (Fig. 5g, h). Wheat appeared sporadically but played a minor role. Dry farming dominated the western mountains, while rice agriculture declined in the northern basins. However, Fenghuangzui maintained its rice-based agricultural system, even though dry farming became evident in the region.

The decline of Jianghan Plain cultures and the southward expansion of the Meishan culture, coupled with a climatic shift toward cooler and drier conditions36,37,38, promoted dry agriculture in the middle Hanshui River region. Unfavorable water and heat conditions, combined with mountainous terrain, made rice cultivation increasingly untenable in the western mountains, solidifying dry agriculture as the dominant agricultural practice.

Archaeobotanical macro-remains, as anthropogenic deposits, provide insights into past human activities, linking behaviors to specific spaces and times. The spatial distribution and density of these remains help identify areas for crop processing, food preparation, and communal consumption, offering a window into agricultural production and redistribution39,40,41,42,43. Ash pits, often repositories for domestic waste, typically contain higher concentrations of charred plant remains, reflecting daily lives. Of the 418 soil samples analyzed, 250 (59.8%) were from ash pits, widely distributed across the 2020 excavation area. By mapping crop grain densities, we identified hotspots (high density) and coldspots (low density), revealing spatial activity patterns within the community. Using each test unit as an analytical unit, we quantified charred crop grains, calculated their densities, and created bubble maps (see Figs. 6–8), where larger bubbles indicate higher grain densities).

Fig. 6
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Bubble map of crop seed distribution in the pits of the Qujialing period at the Fenghuangzui site.

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Fig. 7
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Bubble map of crop seed distribution in the pits of the Shijiahe period at the Fenghuangzui site.

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Fig. 8
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Bubble map of crop seed distribution in the pits of the Meishan period at the Fenghuangzui site.

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In the Qujialing period (5300–4500 cal BP), crop grains were concentrated in the southwest and southern corners of the excavation area (Fig. 6), likely representing primary residential and activity zones. During the Shijiahe period, crop grains were distributed more widely across the site (Fig. 7), suggesting increased residential or activity levels. The southwest corner remained a hotspot, consistent with the Qujialing period, while the eastern area showed fewer remains, indicating less frequent habitation. In the Meishan period, evidence of activity diminished, with traces primarily in the northeastern part of the site (Fig. 8). This shift may reflect changing residential patterns or the site’s decline, but further investigation is required to confirm this inference. Overall, the distribution of crop grains expanded from the southwest and south towards the east and northeast over time. During the Shijiahe period, grains were widely distributed, while in the Meishan period, they were restricted to the northeast. Assuming that more ash pits indicate more significant domestic activity, the charred crop grains reflect the daily lives of Fenghuangzui’s inhabitants. These patterns suggest that Neolithic town life at Fenghuangzui emerged during the Qujialing period, peaked in the Shijiahe period, and declined in the Meishan period.

The archaeobotanical record at a site is influenced by complex pre- and post-depositional processes44. Post-depositional processes, such as water runoff, wind transportation, and topography, can displace plant remains, limiting interpretive accuracy. For instance, the presence of wheat at the Fenghuangzui site is cautiously interpreted as it may result from stratigraphic disturbance. Further radiocarbon dates may shed more light on this issue.

The Fenghuangzui site and surrounding areas were intensively used as rice fields before the 2020 excavation, indicating that the modern environmental conditions support rice farming. Plant macro-remains suggest that Late Neolithic inhabitants cultivated local rice. However, the complete absence of archeological rice spikelet bases in the excavation area implies that rice was pre-processed elsewhere before being transported to the excavation area for consumption.

In archaeobotanical studies, rice spikelet bases are key markers for distinguishing wild from domesticated rice45. Spikelets are typically removed during threshing, a post-harvest process that converts rice stalks into edible grains46. Thus, the presence of spikelet bases indicates on-site threshing, while their absence suggests off-site processing. At Fenghuangzui, all recovered rice remains were grains (n = 2504), with no husks or spikelet bases identified. This pattern, observed across 418 soil samples, is unlikely due to sampling bias. Additionally, just one charred seed of Echinochloa crus-galli, a common rice paddy weed often found at prehistoric sites14,47,48, was recovered. These findings support the hypothesis that rice was threshed and pre-processed elsewhere before being transported to the excavation area.

The scatter plot in Fig. 9 shows no positive correlation between charred crop grains and non-crop seeds recovered through flotation. Excavation units with non-crop seeds show slight variation in quantity, while those with crop grains show significant differences. Given that crop seeds, such as rice, were likely pre-processed elsewhere, non-crop plants were neither related to agricultural production nor transported with crops during harvesting.

Fig. 9: Scatter plot of crop seeds and non-agricultural seeds in the pits of different periods at the Fenghuangzui site.
figure 9

a Qujialing period. b Shijiahe period. c Meishan period.

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We propose that Neolithic inhabitants intentionally utilize non-crop plants. Identified species include Chenopodiaceae (n = 75), P. oleracea (n = 47), Perilla frutescens (n = 7), and wild soybeans (Glycine soja), which may have been consumed as wild vegetables or fodder. These three species collectively account for 50.39% of non-crop seeds, suggesting that wild plants supplemented the human or domestic animal’s diet. Additionally, four fruit kernel fragments (Fig. 4) from the Shijiahe period indicate fruit consumption. Similar patterns are observed at other middle Hanshui River sites, such as Qinglongquan, Gouwan, and Dasi, where Chenopodiaceae, P. oleracea, and P. frutescens were also recovered33,49,50. Western mountainous areas utilized local fruit resources (e.g., Actinidia, Vitis, and Diospyros)51, while the Jianghan Plain relied on fruits (Ziziphus, Diospyros, Vitis, Rubus, Actinidia, and Amygdalus) and aquatic plants (Trapa sp. and Euryale ferox)34. These findings highlight regional differences in wild plant resource utilization.

Analysis of plant macro-remains from Fenghuangzui reveals a stable crop assemblage dominated by rice from the Qujialing to Meishan periods, with limited dry crops (foxtail millet and broomcorn millet) and supplementary wild vegetable collection. The absence of crop processing waste (e.g., spikelet bases and rice weeds) suggests that threshing occurred outside the excavation area. The spatial distribution of charred plant remains in ash pits reflects evolving residential patterns, from the emergence of Qujialing culture to the prosperity of Shijiahe culture and the decline of Meishan culture.

In the Neolithic era, agricultural practices in the middle Hanshui River region exhibited significant regional variation. In western mountainous areas, dry farming (primarily foxtail millet) dominated, with limited rice cultivation, influenced by Central Plains and Jianghan cultures, geography, and climate. In northern basins, rice farming prevailed initially, but the southward expansion of Central Plains culture and arid conditions led to a balance between dry and rice agriculture. In the southern plains, where Fenghuangzui is located, rice dominated in both quantity and ubiquity, with minimal foxtail and broomcorn millet, representing a unique agricultural pattern in the region. Our study highlights the centrality of rice farming at Fenghuangzui, supplemented by limited dry crops and wild plant resources, and underscores the influence of cultural, geographical, and climatic factors on regional agricultural practices.