Goryeo's Capital Move to Ganghwa Island (1240s)

Timeline

1. 1240–1245Ganghwa Island palace city · Ganghwa IslandIn the 1240s the Goryeo king and officials continued handling state affairs on Ganghwa Island; the state name nominally endured while real military and political power lay with the Choe military regime. Using an island capital both avoided the direct Mongol threat to Gaeseong and preserved grain-transport links with the mainland, forming a distinctive 'Gangdu' political order.
2. 1237–1248Ganghwa Island outer wall · Ganghwa IslandKing Gojong ordered the printing of the Tripitaka Koreana on Ganghwa Island, a project begun in 1236 and completed in 1248, seeking Buddhist merit to protect the realm. Meanwhile outer and middle walls were built; by 1250 the outer wall ran about 29 li with 13 gates, giving the island capital both religious and cultural symbolic significance.
3. 1246–1250Ganghwa Island · Ganghwa IslandMongol forces repeatedly failed to cross the sea and take Ganghwa Island; Saritai made a half-hearted attempt in 1232 before turning to Jori fortress, and Amukan's 1246–1248 expedition also failed to threaten the island capital. The move effectively exploited Mongol naval weakness and tidal hazards, letting Goryeo preserve its regime core under Mongol pressure.