Fig. 23: Comparison of fortress distribution to natural village distribution.

Panel 'a' is the distribution map of kernel density based on all village settlements in Tianshui City. Panel 'b' is based on the distribution map of the core density of natural villages in Tianshui City obtained by Panels 'a', and the points of Baozhai villages in Tianshui City are superimposed. It is used to intuitively reflect the degree of correlation between the fortress villages and all villages.