The Battle of Köse Dağ ended the Sultanate of Rum's independence, reducing it to a Mongol client state and opening Anatolia to Ilkhanate dominion.
Key Facts
- Date
- 26 June 1243
- Mongol force size
- 30,000 troops plus Georgian and Armenian auxiliaries
- Rum force size
- 80,000 troops
- Mongol commander
- Baiju
- Rum commander
- Sultan Kaykhusraw II
- Outcome for Rum
- Reduced to client kingdom; vast annual tribute exacted
By the Numbers
Location
Cause → Event → Consequence
Mongol expansion into western Iran in the early 1230s brought the empire into contact with the Sultanate of Rum. Relations deteriorated after Kaykhusraw II took the throne in 1237, and raids on Rum territory began in 1240. In 1242, the Mongol general Baiju captured and sacked Erzurum, escalating tensions into open war and prompting his renewed invasion in 1243.
On 26 June 1243, Kaykhusraw II led an 80,000-strong army to block Baiju's 30,000 Mongol troops, augmented by Georgian and Armenian auxiliaries, at the mountain pass of Köse Dağ. Despite appearing slightly superior for most of the engagement, the Rum army lost cohesion and fled during the night. Baiju, suspecting a trap, did not immediately pursue, but the battlefield was decisively his.
The Sultanate of Rum never recovered from the defeat. The Mongols captured several Anatolian cities and imposed a heavy annual tribute on Rum, reducing it to a vassal state. Its territories were eventually absorbed into the Mongol Ilkhanate, ending Rum's status as a significant independent power in the eastern Mediterranean.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Baiju.
Side B
1 belligerent
Sultan Kaykhusraw II.