Mongol invasion of Kievan Rus': Mongol forces defeated a Kievan Rus' army at the Battle of the Kalka River in present-day Ukraine.

The Mongol Empire invaded and conquered much of Russia in the mid-13th century, sacking numerous cities such as Ryazan, Yaroslavl, Pereyaslavl and Vladimir, including the largest: Kiev and Chernigov. The siege of Kiev in 1240 by the Mongols is generally held to mark the end of the first Russian state of Kievan Rus', which had already been undergoing fragmentation. Many other principalities and urban centres in the northwest and southwest escaped complete destruction or suffered little to no damage from the Mongol invasion, including Galicia–Volhynia, Pskov, Smolensk, Polotsk, Vitebsk, and probably Rostov and Uglich.

The Mongol Empire was the largest contiguous empire in history. Originating in present-day Mongolia in East Asia, the empire at its height stretched from the Sea of Japan to Eastern Europe, extending northward into the Arctic; east and southward into the Indian subcontinent, mounting invasions of Southeast Asia, and conquering the Iranian plateau; and reaching westward as far as the Levant and the Carpathian Mountains.

Kievan Rus', also known as Kyivan Rus', was the first East Slavic state and later an amalgam of principalities in Eastern Europe from the late 9th to the mid-13th century. Encompassing a variety of polities and peoples, including East Slavic, Norse, and Finnic, it was ruled by the Rurik dynasty, founded by the Varangian prince Rurik. The name was coined by Russian historians in the 19th century to describe the period when Kiev was preeminent. At its greatest extent in the mid-11th century, Kievan Rus' stretched from the White Sea in the north to the Black Sea in the south and from the headwaters of the Vistula in the west to the Taman Peninsula in the east, uniting the East Slavic tribes.

The Battle of the Kalka River was fought between the Mongol Empire, whose armies were led by Jebe and Subutai, and a coalition of several Rus' principalities, including Kiev and Galicia-Volhynia, and the Cumans under Köten. They were under the joint command of Mstislav the Bold and Mstislav III of Kiev. The battle was fought on May 31, 1223 on the banks of the Kalka River in present-day Donetsk Oblast, Ukraine, and ended in a decisive Mongol victory.