Many of his students are Kims. So are his fellow teachers, an elementary school alumnus and the owners of restaurants and pubs that he patronizes in his small farming village. Lots of Kims in his neighborhood, too. Such is everyday life for Kim Sun Won, who, obviously, is a Kim too.

He's lived all his 70 years in a tile-roofed home in a clan village, surrounded by people who share his connection to an illustrious ancestor from centuries ago. Other clan villages in South Korea are dominated by Hwangs, Yuns and many other names.

"This is the house where my father, grandfather, great-grandfather and great-great-grandfather lived," Kim said, walking down a small hill dotted with his ancestors' tombs and gravestones. "I've never wanted to abandon my hometown."

Modernization is turning the villages into a fading tradition. Dozens with at least 100 clan members remain, but there were once hundreds. The others have been lost to the frenzy of construction across much of the country, and to young people leaving small-town life for bigger opportunities in Asia's fourth-largest economy. Ancestry does not have the pull it once did for some, perhaps because some Koreans generations ago gained their prestigious surnames by buying them, not through birth.

For Kim, however, ancient family ties remain as tangible as the large earthen tombs behind his house.

As a direct descendant of 17th-century Confucian scholar Kim Jang-saeng, the 70-year-old holds about 15 memorial services per year for his ancestors at his home, a responsibility he calls his "destiny."

"I don't mind living near the tombs," said Kim Sun Won, a retired local civil servant in the city of Nonsan who now teaches filial piety, the life of Kim Jang-saeng and local history at a traditional Confucian school. "I feel secure here because I have the support of all my family clan members here."

Clan villages thrived under Confucian, traditional value systems that prize family connections, filial duty, respect for ancestors and regional ties.

In Kim's Yeonsan village there are now about 130 households associated with his family clan, but there are many more non-Kim households. A generation ago, Kim said there were about up to 300 clan households, mostly extended families.

Clan villages are usually made up of people who share prominent ancestors: royal princes, top officials, revered scholars. The villages preserve ancestral shrines and regularly hold memorial services by burning incense, offering food and liquor at altars and deeply bowing.

In Paju, a city near the North Korean border, two villages are home to dozens of people with the surname Hwang who claim as an ancestor Hwang Hui, a 15th-century prime minister renowned for his moral integrity and righteousness.

"He's like our religion," said Hwang You Yeon, a 69-year-old resident in one of the two villages where Hwang Hui spent most of his post-retirement years. "He's our pride."

Last spring, the Hwangs made headlines when they confronted a ruling-party lawmaker who alleged Hwang Hui took bribes and committed adultery. The lawmaker apologized after the Hwangs threatened to campaign against him.

These days, it's largely the elderly who live in villages associated with their clans. Young people migrate to cities, and while some eventually return, others with different surnames have moved in too. In some cases high-rise apartments have changed the character of once-rural villages.

In a nearby Paju village, seven out of 10 households were once associated with a Yun family. Now the number is about three in 10.

"In those times, there was less individual action. Young people today are spoiled. Aren't they?" said Yun Hoon Duk, a resident in the Yun village. "We had grown up with our grandfathers, uncles and nephews ... so we naturally learned the rules of etiquette."

The clan clusters reveal a fascinating feature of South Korea, where a handful of surnames far outweighs the rest in popularity. More than 20 percent of the country's 50 million people are Kims, from two former South Korean presidents to the South's only Olympic figure skating gold medalist.

All Kims do not belong to the same clan. They are divided among about 350 "bongwans" that are associated with particular locations. Kim Sun Won, for instance, is a Gwangsan Kim, named after a southern town where his first ancestor is believed to have settled. Government surveys in 2000, the most recent census data available, showed there were 286 South Korean surnames and 4,179 bongwans.

The dominance of a few surnames is closely linked to Korea's feudal and Confucian history and the legacy of Japan's colonization of the Korean Peninsula from 1910-1945.

Surnames were usually reserved for nobility and royalty until the 18th century, when some bankrupt aristocrats allowed commoners to be added to their genealogical books, called "jokbo," in return for money.

There are no official records on how many commoners got surnames, but it's believed to be significant because rampant poverty and the lack of efficient state surveillance systems made the forgery of jokbos widespread.

During the Joseon Dynasty, which ruled from 1392 to 1910, the aristocracy grew from less than 10 percent of the population to as much as 70 percent, in large part because of forged jokbos, said Park HongGab, an expert on Korean surnames at the state-run National Institute of Korean History.

When Japan colonized the Korean Peninsula in the early 20th century, it forced every Korean to have a surname. Slaves took their masters' surnames and the poor often picked ones used by high-level aristocrats: Kim, Lee and Park.

"There were slaves, many slaves in the past. But now there's no one who says they are the descendant of slaves," said Kim Jin Woo, a specialist on Korean surnames. "This is why many people don't trust jokbos."

Those who want a prominent lineage can still hire jokbo brokers to fabricate genealogical books. The forgery of the books is linked to Korea's traditional reverence for family background, which has long determined business, social and marital success. More prominent ancestors boost status.

Some records, however, would be quite difficult to fake. Historic clan villages keep centuries-old genealogical books that they say have been handed down from generation to generation. The Hwangs in Paju have a two-volume book written in 1723; the Yun family in Paju keeps woodblocks used to publish its family tree from 1630 to 1863; and Kim Sun Won has a modern version of genealogical books at his home.

The role of ancestral ties in North Korean life is minimal compared to that in the South, though the countries share similar surnames. The North, founded as a socialist republic, has tried to abolish clan systems it calls the legacy of feudalism.

Even so, the system's legacy remains. During a landmark 2000 summit between then-South Korean President Kim Dae-jung and then-North Korean leader Kim Jong Il — father of current leader Kim Jong Un — the two Kims joked about their shared surname but different clans.

"We're really from the same family and we've finally met each other," Kim Jong Il was quoted as saying in North Korean state media.