Reasons Behind the Prevalence of the Surname “Kim” in Korea

If you come across any Korean name, chances are their surname is probably Kim (김). That’s because Kim is the most common last name in South Korea, and it accounts for 21.5% of the country’s population.

Compare this to the United States, where their most popular last name, Smith, only makes up 1% of their total population. It is fascinating and unique to have a significant percentage of a country’s population share an identical surname. But why is there such little disparity? Let us shed some light on this interesting phenomenon.

1. Kim used to be a royal name

The enduring popularity of the Kim family name can be traced back to its royal origins. Kim has its roots in two separate royal families; the Silla dynasty (57BC — 935AD) and the Gaya confederacy (42AD-562AD). When these two kingdoms united, the resulting merger led to Kim becoming one of the most popular family names.

2. Reforming the slave naming system

At the height of the Joseon dynasty, slaves accounted for 50 to 60 percent of the nation’s population. During this period, surnames were a symbol of power and class, and only noblemen possess them. In contrast, slaves were not given a legal name due to the luxury associated with it.

However, this system was abandoned after two consecutive wars against the Qing Dynasty and Japan. These conflicts depleted the dynasty’s wealth and left Joseon deprived of money. The lack of resources prompted the monarchy to reform its naming system, which granted slaves and commoners the right to buy a family name and raise their social status. This reform was intended to bring in more tax revenue as slaves need not pay taxes before the change due to a lack of family name.

The majority of the slave population chose to purchase influential surnames, such as Kim, to flaunt their elevated status. Others opted to adopt the family names of their previous masters. This decision led to an increase in family size for powerful families that owned many slaves.

3. Japan’s occupation of the Korean peninsula

In 1910, after a prolonged war, Korea was annexed and colonised by Japan. To effectively control the peninsula, Japan mandated every adult to report their surname to the colonial administration. This law prompted those without a family name to choose last names such as Kim, burgeoning the numbers of an already popular surname.

Are all Kims the same?

Despite sharing an identical surname, not all Kims are related to one another. A fundamental component of the Korean traditional kinship system is the clan, or bon-gwan, whose last name signifies a shared geographical origin. Thus, various Kims can trace their ancestry to different locations.

In the past, it was forbidden by law to marry someone from the same clan for fear of them being related distantly. There is even an example of this practice in the popular K-drama, Reply 1988, with the protagonists, Sun Woo and Bora, fighting off objections from their mums, who opposed their wedding as they share the same surname and clan.

The government made efforts on three separate occasions in 1978, 1988, and 1996 to legalise marriage between people with the same surname and clan, but public backlash convinced them to backtrack on their decisions. Over time, this concern subsided, and the original law was finally repealed in 1999.


In Korean society, a surname is as much a reflection of the country’s political-economic history as it is a family’s genealogy. Exploring the unique history of the Korean peninsula has revealed to us the fascinating truth behind the country’s lack of diversity in surnames and why so many Koreans have the last name, Kim.

Suppose you are fascinated by Korean history and wish to take a deep dive and explore the nation’s different periods. In that case, it is advisable to learn the Korean language. Familiarity with the language can help you better understand the country’s culture and heritage, as specific nuances may be lost in translation.

We make learning Korean fun by incorporating non-traditional teaching methods in our classes to spark our students’ interest. So, sign up for our Korean language courses today and enjoy exploring this unique culture with a group of like-minded folks as you interact and bond over your shared interest in the Korean language.

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