Cheonghaejin was established originally as a military complex by General Jang Bogo in 828, the third year of King Heungdeok's reign. Jang appealed to Heungdeok to establish a military complex in Cheonghaejin to protect Silla's merchant fleets and coastal residents from pirates. He was granted permission and 10,000 troops. He established a small castle and a military base in Garipo. Cheonghaejin was very successful in its mission; it maintained strong commercial ties with Chinese and Japanese trading ports and successfully protected Silla merchants and coastal residents from pirates. Jang sent envoys called Hoyeoksa for trading activities and cultural exchange. It was resented by many Silla noblemen of small maritime societies because they lost their profits from private maritime trades. The noblemen of Silla sent an assassin, Yeom Jang, to assassinate Jang. After Jang's assassination, the complex was maintained by Yeom Jang himself, but the residents of Cheonghaejin, mourning Jang's death, left Cheonghaejin. They mostly moved to other regions of Silla, while some moved to China or Japan. It is recorded in Samguk Sagi that the central Silla government closed Cheongjaejin in February 851. The remaining residents were then relocated to Byeokgolgun.
Modern times
Cheonghaejin is now located in Wando County, Jeollanam-do, and is a main tourist location in the region. There is a stele commemorating the relocation of residents of Cheongjaejin to Byeokgolgun and various remains of the complex. Remains of various mercantile products and plates have been discovered in Cheongjaejin, which greatly contributed to understanding the life of Silla people.
Historical Site
The historic site of Cheonghaejin is the site of a military fortress dating back to the Unified Silla period located on Jangdo at 734 Jangjwa-ri, Wando-eup, Wando-gun, Jeollanam-do. The distance from Wando to Jangdo is about 180m, which can be covered on foott twice a day when the ebbing tide exposes the seabed. It is a major historical site where in the 9th century during the Unified Silla, General Jang Bogo installed Cheonghaejin and cracked down on pirates and let the place serve as the stronghold for a maritime trading route that dominated the maritime trade in the seas off the three sides of the Korean Peninsula.
Wooden Fence : Presumed to be a wooden fence designed to defend the entrance of the island, Wonmokryeol has a length of 331m and is mostly made of oak posts. When the wooden fence specimen was put to radiocarbon dating, it was identified as dating to the mid-9th century.
Cheonghaejin Castle: Stretching 890m, the castle construction used rammed earth, which arrays in parallel one or two layers of stones at intervals of 5-6m and compacts earth inside the framework to stack up in a robust manner.
Historic Site of Beobhwasa: At the foot of Sanghwang-bong that stands behind Jangjwa-ri lies the old site of Beobhwa-sa reportedly constructed in imitation of Beobhwawon that Jang Bogo built in Chishan, Shandong Province.
ㄷ-Shaped Vestiges of Rammed Earth Construction and the Well: The ㄷ-shaped vestiges of rammed earth construction is a costal structure, which is unexampled not only at home but also in China and Japan. The ㄷ-shaped vestiges of rammed earth construction serves to protect the well and reinforce the outer castle gate. The remaining depth of the well is 5.8m, from which various artifices such as wrinkled vase and iron pieces were excavated.
Oeseongmun : As a passage that connects the inside and outside of the castle, it serves to deter enemy attacks, stage counterattacks, or defeat enemies.
Naeseongmun : It is the second gate inside the castle with a defensive purpose.
Godae : Located at the middle of the castle wall south of Cheonghaejin that runs from east to west, it is a vantage point at the passage that leads inland from overseas, from which it was easy to monitor offshore commercial ships and pirates.
