Jang Bogo’s Cheonghae garrison and the trade of the Yellow Sea

Jang Bogo, called Gungbok in his youth, and his friend Jeong Nyeon went to Tang China and became junior officers of the Wuning army in Xuzhou. Many Silla people then lived along the coasts of Shandong and Jiangsu, and raiders seized Silla villagers and sold them as slaves. According to the New Book of Tang, Jang told the king that ‘all over China Silla people are made slaves’ and asked to guard Cheonghae, a key point on the sea route; the king gave him 10,000 men, and from then on, the Tang history says, no one sold Silla people at sea. The Samguk sagi records the appointment under the fourth month of 828. Remains of the base survive on Jangdo, an islet off Wando: an 890-metre fort of rammed earth and a 331-metre palisade of oak posts radiocarbon-dated to the mid-9th century.

From Cheonghae Jang’s ships controlled the trade of the Yellow Sea. He sent trading envoys to Tang and to Japan, where a former governor of Chikuzen paid him in advance with silk for Chinese goods, and he founded the Lotus Cloister on Mount Chi (Chishan) in Shandong, a temple of the local Silla community, where the Japanese monk Ennin stayed in 839–840 and from which he wrote to ‘Commissioner Jang of Cheonghae’. Jang also became a kingmaker. The prince Kim U-jing fled to Cheonghae in 837, and in 838 Jang gave Jeong Nyeon 5,000 men to win him the throne; the new king, Sinmu, made Jang commissioner of the Gamui army with the revenue of 2,000 households, and his successor Munseong named him ‘General Who Guards the Sea’. The New Book of Tang, quoting the poet Du Mu, praised Jang for welcoming his old rival Jeong Nyeon and compared him with Guo Ziyi.

His power alarmed the nobles of the capital. In 845 King Munseong wished to take Jang’s daughter as a secondary queen, but the courtiers objected that Jang was ‘a man of the sea islands’. According to the Samguk sagi, Jang rose in revolt in the spring of 846, and Yeom Jang of Muju, pretending to defect, was received as an honoured guest and killed him with his own sword when he was drunk. Japanese records date his death earlier: islanders who fled to Kyushu said that he had died in the 11th month of the previous year — late 841 or early 842 — and this date is preferred by the National Institute of Korean History. In 851 the court abolished the garrison and moved its people to Byeokgol.