Yeom Jang was a Silla

Silla

Silla was one of the Three Kingdoms of Korea, and one of the longest sustained dynasties in...

 general who is best known for assassinating Jang Bogo

Jang Bogo

Jang Bogo , also known as Gungbok, rose to prominence in Korea in the late Unified Silla period as a powerful maritime figure who for several decades effectively controlled the West Sea and Korean coast between southwestern Korea and China's Shandong peninsula...

. Yeom had actually been a subordinate of Jang Bogo, but their relationship apparently deteriorated as he was once punished by Jang for having been personally engaged in slave trade.

Eventually, Yeom turned to Kim Yang (김양, 金陽, 808-857), actual power of the Korean court, under whose direction, he went on a quest to kill Jang Bogo.