The project maps aspects of Chinese history from 222 B.C.E to 1911 C.E. This map concerns Liangzhe province in 1077. The background shows population density, the colored circles represent the tax quotas for commercial tax collection offices. "By 1077, in contrast to earlier periods," explains Peter Bol, Carswell professor of East Asian languages and civilizations, "the hierarchy of economic central places, as represented by the tax quotas, no longer corresponded to the hierarchy of administrative central places--the counties and, above them, the prefectures. This was a sign that a commercial revolution was taking place, because the economy was no longer being subordinated to the administrative system. Some non-administrative towns have more economic activity than their county seats, some county seats are more active than the seats of the prefectures to which they belong. If this can be extended to all of China--and it can be, since we have the figures--we will be on the way to showing how economic activity was distributed and where the important trade routes were."