Jangbogo went to China to struggle against hard living and performed a meritorious deed for a corps led by Wangjiheung during the Tang Dynasty. Because of his achievements, he was promoted to major general. However, he left the army because the Tang dynasty reduced the armed forces after the subjugation of Bunjin. He brought together people from the Shilla who lived in China and organized a network for trade until 828 when he returned home. He took control of the West sea trade routes as the family of Lee Jeong-ki collapsed. He constructed Cheong-hae-jin in Wando, his hometown and a key point on the sea route. He justified his control over small business groups of the west and south sea of Korea and the east and south sea of China by keeping pirates away. His trade groups controlled foreign trade of three countries: Shilla, the Tang Dynasty of China and Japan. They advanced into the Namyang sea route that connected Persia, India, Southeast Asia, and China. Jangbogo monopolized the trade among the three northeast Asian Kingdoms and became very powerful. He overcame the limitation of social positions through a marriage with the royal family, and had a great influence on decision of domestic affairs, but he was assassinated by Yeorn -jang who came from Muju. Although he was killed unexpectedly, he was a leader among the powerful families from every corner of Korea.