Which Song fortress resisted Mongol sieges for over 30 years?

The Song fortress that resisted Mongol attacks for more than 30 years was Diaoyucheng, also called Diaoyu Fortress. Built on Diaoyu Mountain near modern Hechuan in Chongqing, it occupied steep terrain surrounded by rivers, making it exceptionally difficult to assault.

The fortress became a major defensive position during the Mongol war against the Southern Song. From 1243 to 1279, its garrison endured repeated attacks and more than 200 military confrontations. In 1259, Möngke Khan personally led a siege that lasted roughly five months. The fortress held, and Möngke died during the campaign, forcing a major Mongol withdrawal.

Diaoyucheng’s resistance had consequences far beyond one battlefield. Möngke’s death intensified the succession struggle between Kublai Khan and Ariq Böke and disrupted Mongol campaigns in several regions. Kublai eventually completed the conquest of the Song in 1279. Diaoyu Fortress finally surrendered that year, shortly before the dynasty’s collapse; its commanders reportedly chose death rather than submit.