Fig. 9: Evolution of negative sentiment towards nomadic ethnic groups in ancient Chinese history.

a Co-occurring vocabulary of Xiongnu in history books recording the Han dynasty. b Co-occurring vocabulary of Mongolia in history books recording the Yuan dynasty. c Frequency changes of nomadic ethnic group names in ancient Chinese history books. d Evolution of the negative sentiment contained in the co-occurring vocabulary of foreign ethnic group names, calculated within ancient Chinese history books. Each ethnic group is represented by a distinct color. The striped bars indicate that that ethnic group established the regime recorded by these historical texts. The bottom of the images is labelled with the corresponding years in the Common Era for each dynasty. a, b, c are screenshots of the platform; d is handmade.