Why 20% of South Koreans Have ‘Kim’ For a Last Name

While not ALL Koreans have those last names, an overwhelming number of them do. According to The Economist, 1 in 5 South Koreans is a Kim or a Lee and 1 in 10 is a Park — those three names alone account for almost half the population of South Korea, which is just over 50 million people. So how did so many millions of people end up with just a handful of different last names?

Korean surnames are a relatively new invention. It was rare to find someone with a family name during Korea’s Joseon Dynasty, which lasted from 1392 to 1910. Family names were a luxury and really only belonged to Korean nobility.

Before the year 1000, Korean King Wang Geon, who founded the Goryeo dynasty, decided to allow select people to adopt a surname in order to distinguish who was a loyal servant of the court. Most of these select people came from elite families and they would take a civil-service examination as a way to advance their family. Whoever passed the exam got to register a surname and their family name would be recorded in a genealogical book.

Eventually, members of the merchant class could also take the exam and adopt a surname. It soon became possible for people with enough money to just buy a genealogy book from an elite family, usually one that had become bankrupt, and fully adopt that family’s name as their own. By the late 1700s, people began to catch on and started forging their own family name records. For a little bit of money, a stranger could even buy their way into a family’s genealogical book and take the name of a noble family.

As you can guess by now, surnames like Kim, Lee and Park were family names that once belonged only to royalty. As the centuries passed, commoners were quick to adopt those names as their own — and they still do.

In the later part of the Joseon Dynasty, the few surnames among the people had become so popular that no one could be sure who was related by blood. In 1894, Korea got rid of their class-based system, which allowed literally anyone to adopt a last name, and of course many people picked among the most popular names. The king eventually made it illegal for people with the same last names to marry (a ban that was lifted in 1997) and by 1909, everyone was required to register their surname with the state.

Today, those few surnames continue to grow. Other Asian ethnicities looking to become naturalized Korean citizens, whether they are Vietnamese, Chinese or Filipino, still choose among the most popular names of Kim, Lee, Park and Choi.

Here’s a bonus fact: The few ancient names that are now widely popular in South Korea originated from China and were adopted around the 7th century. Most surnames are formed from a single Chinese character and used to include the clan’s regional origin.