How to distinguish the black flag and white flag villages in Putian

In ancient Putian, in order to facilitate governance and management, local officials divided the two adjacent villages into "Black Flag Village" and "White Flag Village". Villages with the same color flag are considered friendly villages, while villages with different color flags become enemy villages. This distinction led to extremely fierce fighting between Black Flag Village and White Flag Village in ancient times, but it also safeguarded the interests of the rulers.