Leong San Tong Khoo Kongsi and its subclans, Boon San Tong Khoo Kongsi and Khoo Si Toon Keng Tong Khoo Kongsi, do not represent every Chinese with the surname of Khoo. Instead, only those whose ancestral origin is from Sin Kang Seah, Sin Aun Village, Sam Toh District, Hai Teng County, Chiang Chew Prefecture, Hokkien Province, China are accepted as clansmen.
Sin Kang Seah is presently Sin Aun Village in Xing Lin District, Xing Lin Town, Amoy (Xiamen), which is under the administration of the Hai Cheng Department of Amoy City Council. This 10 sq km area, which is some 8 km west of the island of Amoy, is situated at the estuary of Sin Kang River, a downstream branch of Kew Leong River. It was a typical clan village of a single surname in costal Southern Fujian. Of its total population of 7000, 78 percent have the surname Khoo.
The Khoos of Sin Aun Village and Leong San Tong Khoo Kongsi, Penang have the same progenitor, who is Khoo Chian Eng. According to The Genealogy of the Sin Kang Khoo and Chan Clans, Khoo Chian Eng was the son of a Chan family. He was a descendant of Chan Yan Si of Oon Leong during the Tang Dynasty, the 14th generation descendant of Chan Leong Kong who was an advisor of the emperor during the Song Dynasty, and the 5th generation descendant of Chan Kong Cheok, the founder of Chan Chu Aun Village, Amoy.
Chan Yan Si who was an assistant trainer in the army of the late Tang Dynasty and his whole family who followed the troop of Ong Teoh (Wang Chao), migrated from Henan Province southward to Oon Leong (Leong San), Nan Aun County, Chuan Chiew Prefecture, Fujian in 885 – 886 to avoid the catastrophe of Huang Chao Rebellion. Chan Kong Cheok, the 18th generation descendant of Chan Yan Si, then moved to Chan Chu Aun, Amoy, where his lineage passed through five generations before the birth of Chian Eng Kong.
Chian Eng Kong was the 4th son of Chan Cheong Kong. About 650 years ago, during the late Yuan Dynasty, he moved to San Peng Ang in Tong Aun County and married Saw See Cheng, who later gave birth to a son named Buan Seng. The family then moved to Teh Toon (later Sin Kang). There Chian Eng Kong inherited numerous assets from a Khoo family. Subsequent generations accepted him as the progenitor of the Khoo clan of Sin Kang Village, Hai Teng County.
In early Ming Dynasty (1380), his son, Buan Seng Kong who settled down in the same place, added the surname of Khoo to his paternal surname. His descendants then adopted the surname of Khoo.
The second generation Khoo Buan Seng had two sons, namely Tua Huat (Guan Heng Kong) and Cheng Huat (Guan Teong Kong). From the third generation on, the family expanded and became a big clan. For the past 650 years, the descendants of the Sin Kang Khoo Clan spread all over China as well as Taiwan, The Philippines, Indonesia, Myanmar, Thailand, Malaysia, Singapore and some European and American countries.
Originally the Chinese character of Khoo had simpler strokes. During the Qing Dynasty, the emperor ordered those having the surname of Khoo (丘 Qiu) to add the radical to become 邱 as a mark of respect for the sage Confucius whose personal name was 丘.