The Battle of Kse Da was fought between the Sultanate of Rum ruled by the Seljuq dynasty and the Mongol Empire on June 26, 1243 at the defile of Kse Da, a location between Erzincan and Gmhane in modern northeastern Turkey. The Mongols achieved a decisive victory.

The Seljuk dynasty, or Seljukids ( SEL-chuuk; Persian: آل سلجوق Al-e Saljuq, alternatively spelled as Seljuqs or Saljuqs), also known as Seljuk Turks, Seljuk Turkomans or the Saljuqids , was an Oghuz Turkic Sunni Muslim dynasty that gradually became Persianate and contributed to the Turco-Persian tradition in the medieval Middle East and Central Asia. The Seljuks established both the Seljuk Empire and the Sultanate of Rum, which at their heights stretched from Iran to Anatolia, and were targets of the First Crusade.