Ancient Changan, China

In 754 AD, there were 1,859 cities in Tang China. All of them served as seats of government administration and were closely overseen by the central government. At this time,the largest cities in China were the two capitals, Changan in the west, and Luoyang in the east. Changan with a population of 2,000,000 may have been the largest city in the world. Changan began serving as the main capital of the Tang dynasty in 618.