Kim, Lee, Park — The Country Where Three Surnames Cover Half the Population, and the Thing Called Bon-gwan

Spend three days in Seoul and something odd starts to happen: every surname you meet seems to repeat. The guesthouse owner is Mr. Kim. Yesterday’s taxi driver was Mr. Kim. Today the barista’s name tag reads Kim. It happens far too often to be coincidence.

And it isn’t coincidence. In Korea, your odds of meeting a Kim are a little better than one in five.

Do three surnames really cover half the population?

Not quite half — 44.6%, to be precise.

The most recent large-scale count is the 2015 Population and Housing Census. Statistics Korea runs a full census of surnames and bon-gwan roughly every 15 years, and 2015 is still the latest. It found 10,689,959 Kims, 7,307,068 Lees, and 4,192,074 Parks. Together that’s 22,189,101 people — 44.6% of the 49.7 million Korean nationals at the time.

Here are the top 20 surnames as of 2015. Because each hanja counts as a separate surname, note that you won’t see two surnames with the same sound — they’re treated as entirely different families.

👥 Korea's top 20 surnames by population (2015 Population and Housing Census, counted by hanja)

Add all twenty together and you get 77.9%. There are 5,582 surnames in total, yet these twenty account for more than three-quarters of the population.

So are all Kims related to each other?

No — and this is where foreigners most often trip over the Korean surname system.

To a Korean, a surname is just the first character of a name tag, not an actual kinship unit. The real unit is the bon-gwan (clan seat), also called the gwanhyang (貫鄕) or simply the bon (本). It’s the old place-name of the region where a family’s sijo (founding ancestor) settled, attached before the surname. Gimhae Kim, Gyeongju Kim, Jeonju Lee, Miryang Park — those first two characters are the bon-gwan.

There are only around 300 surnames in Korea, but count the bon-gwan and you get 36,744 as of 2015. That means a single surname splits into dozens or hundreds of branches. Of these, 858 bon-gwan have more than 1,000 members, and those 858 account for 97.8% of the population.

Bon-gwan too are heavily concentrated in a few regions. The Gimhae Kim clan alone is nearly 9% of the entire population.

🏯 The most populous bon-gwan (2015, including merged similar bon-gwan)

Scan the list and you’ll notice something: every bon-gwan here is in the southern half of the Korean Peninsula. The system took shape between late Silla and early Goryeo, so the names cluster south of Pyongyang and Wonsan — the territory within the borders of the time. On a map, most Koreans’ ancestral addresses sit below Seoul.

Did everyone always have a surname?

No — and that’s the real reason for the Kim-Lee-Park concentration.

During the Three Kingdoms period, only royalty and a tiny nobility had surnames. In Silla, the three surnames Park, Seok, and Kim rotated the throne, and records say King Yuri Isageum granted the surnames Lee, Choi, Jeong, Son, Bae, and Seol to six village chiefs. A surname, in other words, began as a certificate of privilege.

In Goryeo, a 1055 rule barred anyone without a surname from sitting the civil service exams. To hold office you now needed a surname, and so surnames and bon-gwan took root among the ruling class first. Still, most of the population remained surname-less.

📜 How the number of Korean surnames changed across historical records

The game changer was the late Joseon period. The Imjin War and the Manchu invasions shook the rigid class order, and it became common for wealthy commoners to buy jokbo from fallen yangban aristocrats. Records from 1764 even show a middle-class man named Kim Gyeong-hui caught forging and selling genealogies. The Silhak scholar Jeong Yak-yong wrote separately about the evils of genealogy forgery.

The decisive blow came in 1909, when the Minjeokbeop (the 1909 Civil Registration Law) made it compulsory for everyone to hold a surname and a bon. People who had none had to pick one at the registration desk, and a large share chose the most common, most prestigious surname in their area. That’s how Kim, Lee, and Park exploded within a single generation.

So the reason one in five Koreans is a Kim isn’t that King Kim Suro’s descendants multiplied unusually well. It’s that people chose the name during the two centuries when the class system was collapsing. In Korea, a surname is less a record of bloodlines than a piece of social history from the moment modernity began.

Does your surname change when you marry?

It doesn’t. Korea is a bububyeolseong country — couples keep their own surnames.

The reason is surprisingly simple. In Korea, a surname was never a mark of belonging to your husband, but a marker of your father’s bloodline. Marriage doesn’t change who your father is, so there was no reason for the surname to change. A daughter-in-law was recorded in her in-laws’ jokbo with her own surname intact, next to her husband.

Which is why it’s perfectly normal in a Korean household for only the mother to have a different surname. Kim Min-su’s mother being Park Yeong-hui isn’t a sign of remarriage or anything unusual. It’s also why teachers don’t call a child’s mother by her husband’s surname at school.

⚖️ The rules for a child's surname — before and after the 2005 civil law amendment

That last row matters more than you’d think. The landmark case came in 2008, when the actress Choi Jin-sil petitioned to change her two children’s surname from their father’s “Jo” to her own “Choi” — and the court granted it. It was the moment the old belief that a surname can never be changed actually broke.

You’re saying people with the same surname couldn’t marry?

More precisely, you couldn’t marry if your surname and your bon-gwan were both the same. That’s the dongseong-dongbon — the same-surname-same-bon-gwan marriage ban.

It began with the introduction of Neo-Confucianism in early Joseon, became customary law under Japanese colonial rule, and was written into statute in the Civil Code that took effect in 1960. The problem was that the rule caught far too many people. Two Gimhae Kims could be so distantly related that no one could calculate the degree of kinship — yet simply being among those four million people barred them from registering a marriage.

📅 How the same-surname-same-bon-gwan marriage ban disappeared

So today, two Gimhae Kims can marry without issue as long as they’re beyond the 8th degree of kinship. Custom, though, dies slower than law. Some in the older generation still balk at it, and a culture of caution lingers around families like the Gimhae Kim and Gimhae Heo clans — different surnames, but traditionally said to have split from the same founding ancestor.

Why is it Kim, not Gim?

Because the official romanization and the actual spelling parted ways.

Applied strictly, Korean romanization gives Gim for 김, I for 이, Bak for 박, and Choe for 최. But surnames were made an exception: you can keep a customary spelling that’s already established on your passport. As a result, you almost never see the “correct” spellings on real passports.

🛂 How surnames were actually spelled on 63,000 passports (2007 survey)

Kim, Lee, and Park are effectively standardized; only Jeong splits three ways. There are even cases where a father writes “Shim” and his son “Sim” within the same family — because whatever you pick on your first passport application sticks.

Park is especially misleading. It’s written “Park” but the Korean sound has no “r” at all. The spelling froze from the British-English pronunciation of “park”, so in front of Koreans you’re better off saying something close to “Bak” rather than “Park”. Likewise, “Lee” has no “l” or “r” sound — it’s just “Ee”.

Are there two-syllable surnames?

There are — but they’re rare. Korean surnames are overwhelmingly one syllable, and all the two-syllable ones combined don’t reach 50,000 people.

🀄 Two-syllable surnames by population (2015)

Two-syllable surnames are easy to misread. “Namgung Min” isn’t a Nam with the given name “Gung-min” — it’s a Namgung named Min. “Seonu Yong-nyeo” isn’t a Seon, but a Seonu. Even Koreans sometimes split the name box wrong, so the person will usually explain first.

Can foreigners create a Korean surname?

Yes. It’s called changseong-changbon — literally, creating a new surname and bon-gwan.

Anyone who acquires Korean nationality can, with court approval, create a new surname and bon-gwan. Some simply transcribe their original surname into hangul and keep it; others pick a Korean-style surname and attach a new bon-gwan. According to the Supreme Court’s judicial yearbook, approvals of changseong-changbon for naturalized citizens averaged 7,113 a year from 2014 to 2018.

This is why the surname count exploded to 5,582 in 2015. Only 1,507 of these can be written in hanja; the other 4,075 have no characters at all. As of 2013, 4,332 surnames had ten or fewer bearers, and 3,025 of those had exactly one. The longest surname on record ran to ten syllables.

So why is this story interesting?

In Korea, a surname tells you almost nothing about a person’s identity. Being a Kim says nothing about them — after all, 21% of the country is Kim. Instead, bon-gwan and jokbo filled that gap, and even those were, in large part, newly made or bought in the late Joseon period.

So the Kims you meet in Seoul — the taxi driver, the cafe worker, the guesthouse owner — are far more likely to be strangers to each other. Yet the name remains so common because, once, it was the best name a person could have.

Go to Gimhae and you’ll find the Royal Tomb of King Suro. Most of the people bowing before it probably have no genetic link to King Kim Suro at all. Still, they all come. In Korea, roots turned out to be less about blood than about choice and records — and that’s precisely what makes the whole system fascinating.