Chang Pogo

According to the earliest Japanese, Chinese, and Korean sources Chang Pogo was the son of a fisherman from Wan Island lying off the southwestern coast of the Korean peninsular. He migrated to Tang China as a youth and pursued a successful military career in the service of the Tang dynasty, rising to the rank of captain. At that time, Korea was under the rule of the Silla Dynasty (57 BC - AD 935). Korea's foreign trade with Tang China and Japan flourished, and these commercial activities led to the establishment of Korean settlements called Sillabang or Silla Quarter on the Shantung Peninsula and on the coast of Kiangsu province, China.

Chang Pogo returned to Korea in 828 and established the military headquarters of Ch'ônghae Garrison on Wan Island. He raised a private army and navy, patrolled the south coast of Korea and put an end to the activities of Chinese pirates who had frequently plundered Korean coastal towns and took the inhabitants to sell as slaves.

In addition he controlled the trade with China and Japan and became a virtual merchant prince of the East Asian region. History relates that the downfall of Chang Pogo was associated with his attempt to marry his daughter to King Munsông. In the face of protests from the aristocracy, however, the new king was prevented from taking Chang Pogo's daughter as his second queen because of Chang's common social origins. In retaliation Chang Pogo revolted against the king but was killed at the hands of the assassin sent by the king, Yôm Chang, in 846. Chang's stronghold, the Ch'ônghae Garrison on Wan Island, was subsequently demolished in 851.

The downfall of Chang Pogo, his navy, and island garrison also marked the end of Korea's brief dominance in the East Asian maritime trade.