1 Korean: there are four Chinese characters for the surname Yu. Some sources indicate the existence of as many as 230 clans, but only about twenty can be positively documented. Several of the clans are of Chinese origin. The largest Yu clan, the Munhwa Yu, was founded by a man named Ch’a Tal. Ch’a's fifth great-grandfather had been involved in an attempt to overthrow the Shilla king. To avoid prosecution, the ancestor fled to Munhwa and changed his surname, first to that of his maternal grandmother, Yang, and then to Yu. Many years later, Ch’a Tal assisted Wang Kŏn to establish the Koryŏ Kingdom. Ch’a was recognized for his support and was rewarded accordingly. Ch’a's eldest son began again to use the Ch’a surname, but his younger son continued to use Yu. The Munhwa Yu clan, along with the Andong Kwŏn clan, possesses one of the oldest extant clan genealogies in Korea.2 Chinese 余: in the Spring and Autumn period ( 722–481 bc ) there lived in the state of Qin a high counselor called You Yu, whose descendants took part of their forebear's ‘style name’, Yu, as their surname.3 Chinese 于: from the name of a territory granted by Wu Wang , the first king ( 1122–1116 bc ) of the Zhou dynasty, to his second son. Some of his descendants adopted a simplified version of the character for Yu as their surname.
Dictionary of American Family Names © Patrick Hanks 2003, 2006.