One of the most striking things you realize after spending time in China is how certain last names are very, very common. When I taught high-school English in Jiangsu Province in 2004, I remember there being at least eight—out of a class of about 30—students surnamed Wang, and two of those shared a first name. Fortunately, all of my students adopted English nicknames, making it easier for me to remember who was who.
For a country of 1.3 billion people, there is a remarkably small number of common last names in China. An estimated 87 percent of the population shares one of 100 surnames, and more than one in five Chinese citizens is surnamed Li, Wang, or Zhang: more than 275 million people in all. (By contrast, 90 percent of the United States population encompasses over 150,000 different last names).
Less known, however, is that the most common Chinese names have a geographic “base” within the country. These fascinating maps, put together by China-focused writer Andrew Stokols using data from this site, tell us where Chinese names are most heavily concentrated in the country. Li, Wang, and Zhang, which comprise over 20 percent of the population, are most commonly found in China's northeast, where the ethnic Han majority is most predominant. Here is a map, for example, of the surname Li: