Fangyan (book)

Yang collected regionalisms from many sources, particularly the 'light carriage' (輶軒 yóuxuān) surveys made during the Zhou and Qin dynasties, where imperial emissaries were sent into the countryside annually to record folk songs and idioms from across China, reaching as far north as Korea.

From the Pass, east- and west-ward [Eastern and Western China], some call it also bodu.

Serruys also applied the techniques of modern dialectology to the distribution of regional words, identifying dialect areas and their relationships.

[7] Based on this, topolect has been used to characterize other speech varieties where an identification as either language or dialect would be controversial.

In all of these situations, an identification of distinct languages by the straightforward criterion of mutual intelligibility may not be politically or socially acceptable to a significant number of scholars.