Mongol forces under Batu and Subutai rout the Hungarian army during the largest Mongol incursion into Europe.
Date given in the Julian calendar.
During the Mongol invasion of Europe, Mongol forces defeat a Polish-led army in Silesia; two days later they rout the Hungarians at Mohi.
Forces of Novgorod led by Alexander Nevsky defeat the German knights of the Livonian Order on frozen Lake Peipus.
Mongol armies under Batu devastate the Rus' principalities and take Kiev in 1240, beginning over two centuries of Golden Horde domination.
Mongol and Southern Song forces take Caizhou, ending the Jurchen Jin dynasty in northern China.
The founder of the Mongol Empire dies during the campaign against Western Xia; his heirs continue its expansion.
Mongol forces under Uriyangqadai occupy Thăng Long but withdraw after the Battle of Đông Bộ Đầu.