Koma clan
The Koma clan was an immigrant from Korea that was active in Japan since the Asuka period. The clan claimed to be the royal family that descended from Prince Ko Yak'gwang of Goguryeo, who became known as "Genbu Jakkō" and later as "Koma no Jakkō".
History
Prince Ko Yak'gwang was a son of the 28th and last King of Goguryeo, Bojang. In 666, after a power struggle with his brothers or as refuge from Tang China's attack, he came to the old capital of Asuka in Japan during the reign of Emperor Tenji. Goguryeo fell to Tang China in 668 and in 699 his brother Ko Tŏngmu founded Lesser Goguryeo. The characters "高麗" can also be read as "Goryeo" instead of Koma.In 703, the exiled prince Ko Yak'gwang was given the court rank of Junior Fifth Rank, Lower Grade by Emperor Monmu and became a lower ranking official. In 716 A.D., Jakkō was instructed to gather the 1,799 Goguryeo refugees who initially came with him, from all over Japan and settle them in the wilderness of the Musashino Plain with a commanding view of the mountains. Jakkō was to be their tribal chief and representative. When Jakkō died, the Koma Shrine was built to memorialize him. Next to the Koma Shrine, settlers from Goguryeo founded the Shoden-in Buddhist Temple to mark Jakkō's tomb.
For centuries, they thrived in the area and kept within their own family. The Koma Shrine remains a symbol of the ancient ties between Korea and Japan. Today, Jakkō's 60th linear descendant, Koma Fumiyasu, is a Shinto priest at his family's ancestral shrine. Built in Korea's shamanist tradition, the building took its present form when the Meiji government forced all worshipers to adopt state Shinto. It is one of hundreds of Shinto shrines across Japan that were built by Korean immigrants. The shrine became an important fixture in propagating the ancient ties between Korea and Japan. Today, the shrine serves as a symbol of friendship between Japan and Korea.
The Koma District that was given to the Goguryeo people stretched from the foothills of the mountains throughout the vast flatlands of Musashino all the way to today's Sayama city. For many centuries, the Koma people married only among their own clan, and they managed to stay out of most of the Japanese clan wars that later ravaged the country. They thrived and were a powerful force in their area.
It was later believed that the Koma family had an influence on the origin of Samurai culture. They brought horses, iron weaponry, armor making skills, and other skills to Japan. After a few centuries following their arrival to Japan, horse-riding warriors started to emerge here and there with iron weaponry and armor in the Kanto area, which includes their settled district.