Ganghwa, incorporated into Incheon metropolitan city from Gyounggido province in 1995, has been recognized as preserved most important history of Korean peninsula from the prehistoric age to modern times.
Relics and remains of prehistoric age, old stone age and new stone age were found of their various vestiges in Jangjeongni, Sagiri, Dongmagni and others respectively in the symbolic huge stone relics of bronze age, more than 80 dolmens were discovered in the vicinity of Bugeunni and neighbouring area, of which giant tombs revealed the existence of inhabitant there.
Especially, there we have Chamseongdan altar atop of Mt. Manisan where Dangun dedicated sacrifice to Heaven and his three sons built a legendary Samnangseong castle and relics of Bongcheondae, Bonggaji, Bongeunsa temple, Stone Buddah statue relating to the tales of Bong's family apparently signify the Ganghwa a holy land of Korea and the peoples throughout it's history.
The major stage of Ganghwa history came around the late period of Goryeo dynasty.
During the national conflict against Mongolian's invasion, the capital was transferred to Ganghwa from Gaeseong for the period of 1232 and 1270. With such vestiges of Goryeo palace site and fortress etc.
Ganghwa was deemed a most appropriate refuge to keep themselves safely from the invasion of Mongolian forces. Especially, world widely recognized treasure; Palman daejanggyeong, 80,000 sheets of Buddah's scriptures (other name Jaejo daejanggyeong) could be possibly engraved during the invasion of 1236 through 1251. It is our significant surprise to learn those great cultural assets accomplished during the national suffering ages.
The importance of Ganghwa as a refuge shelter had been successively chosen during Joseon dynasty;
two incidents Manchurian invasion, Jeongmyo-horan, in 1627 and Byeongja horan 1636 enforced the King Injo to take refuge in the island, taking advantage of the natural strategic environment to defend themselves from the enemy attack. Thereafter, Ganghwado had accordingly installed many military facilities to meet the pre-requisite of defending capital; castles, military bases, forts, outposts, batteries and beacon fire mounds etc.
In the late of Joseon dynasty, a few incidents of the western power's invasion and Japan made the Ganghwado the most important military base to have the capital fully defended.
First incident was Byeongin-yangyo outbreaking in 1866 between Joseon and France. Daewongun, the actual ruler and father of King Gojong , was a man of isolated national policy of which he executed a religious oppression over the catholic priesthood and believers that had actually caused the hostilities to be opened by France. The second one was Sinmi-yangyo occurred in 1871 of which American navy opened hostilities upon the Jeoseon's denial of their proposal for a trade port opening. The third one was the Japanese ship Unyomaru happened in 1875. This was an incidental clash between Joseon and Japan in the offshore of Ganghwado upon Jeoseon's refusal of Japan's demand for the trade port opening. For the compensation on the Unyomaru's incident, a treaty of amity was bilaterally concluded in Ganghwado. This is a historical event that Joseon initiated to adopt the open door policy toward the world.