Chang Po-go (died 846) was a Korean adventurer and merchant prince whose name was once synonymous with Korean maritime dominance in eastern Asia in the early 9th century.

Son of a fisherman from Wan Island off the south-western coast of the Korean peninsula, Chang Po-go early migrated to T'ang China, where he rose to be a captain in Hsü-chou in the lower Huai River valley. Returning to Korea in 828, he alerted the throne over the danger of Chinese piracy in the Yellow Sea, whereupon the King appointed him commissioner of Ch'onghaejin, the military headquarters of Wan Island. Chang raised a private navy, which at times numbered 10,000 men, by which he controlled the ocean commerce between China, Korea, and Japan.

The ships engaged in this international trade were owned and manned by Chang, and Korean trading communities flourished along the southern coast of the Shantung Peninsula and the...