Mongol invasions progressed throughout the 13th century, resulting in the vast Mongol Empire which covered much of Asia and Eastern Europe by 1300.

The Mongol Empire emerged in the course of the 13th century by a series of conquests and invasions throughout Central and Western Asia, reaching Eastern Europe by the 1240s. The speed and extent of territorial expansion parallels the Hunnic/Turkic conquests of the Migration period (the 6th century Turkic Khaganate).

The territorial gains of the Mongols persisted into the 15th century in Persia (Timurid dynasty) and in Russia (Tatar and Mongol raids against Russian states), and into the 19th century in India (the Mughal Empire).

Genghis Khan forged the initial Mongol Empire in Central Asia, starting with the unification of the Mongol and Turkic central Asian confederations such as Merkits, Tartars, Mongols, and Uighurs. He then continued expansion of the Empire via invasion of the Khwarezmid Empire in what is modern-day Khorazm, Uzbekistan.

Large areas of Islamic Central Asia and northeastern Iran were seriously depopulated, as every city or town that resisted the Mongols was subject to destruction. In Termez, on the Oxus: "all the people, both men and women, were driven out onto the plain, and divided in accordance with their usual custom, then they were all slain". Each soldier was required to execute a certain number of persons, with the number varying according to circumstances. For example, after the conquest of Urgench, each Mongol warrior – in an army group that might have consisted of two tumens (units of 10,000) – was required to execute 24 people.