Why 1.2 billion people share the same 100 surnames in China

(CNN)If you stop a random person on the street in China, there's a pretty good chance their surname would be either Wang, Li, Zhang, Liu or Chen.

That's because those are the five most common surnames in China -- shared by more than 433 million people, or 30% of the population, according to government figures.
With 1.37 billion citizens, China has the world's largest population, but has one of the smallest surname pools. Only about 6,000 surnames are in use, according to the Ministry of Public Security. And the vast majority of the population -- almost 86% -- share just 100 of those surnames.
    To put that in perspective, the United States -- with less than a quarter of China's population -- reported 6.3 million surnames in its 2010 census. The majority of those names were only reported once.
    There are a few reasons for this: China is less racially diverse than countries such as the US, where a wealth of minority groups increase surname diversity. It also has to do with language; you can't just add a random stroke to a Chinese character and create a new surname, the way you can add a letter to an English name.
    But there's also another factor at play: technology.
    China's digital revolution has transformed daily life, and many of these systems rely on a limited list of standardized Chinese characters.
    That means people with rare characters in their names, which aren't compatible with existing computer systems, can get left behind -- pushing many to change their names for the sake of convenience, even if it means abandoning centuries of heritage and language.

    How some surnames went extinct

    It wasn't always this way. Throughout its long history, China has recorded more than 20,000 surnames, according to Chen Jiawei, an associate professor at Beijing Normal University, who has researched Chinese surname distribution. Some researchers place that estimate at up to 23,000 surnames.
    "The culture of surnames has been passed down in our country for thousands of years, with a deep and broad influence," said the Ministry of Public Security in its 2019 annual nationwide survey on surnames. "Throughout history, the surnames have developed and differentiated, forming more than 6,000 surnames in use today."
    The first records of Chinese surnames stretch back to "the era of bronze, bamboo and silk script," according to the ministry -- referring to when people wrote on raw materials in the Shang and Zhou dynasties (1600-256 BC), before the invention of paper.
    By the Song Dynasty (960-1279 AD), a book called the "Hundred Family Surnames," listing several hundred of the most common surnames, had become a classic text taught to children.