In the 12th century, the Khwarezmid Empire was founded and, in the early 13th century, ruled over all of Persia under the Shah ʿAlāʾ al-Dīn Muhammad II (1200–1220).

In 1141, Yelü Dashi won the battle of Qatwan against a Seljuk army commanded by Sanjar, as a result, Khwarezm became a vassal of the Kara-Khitan Khanate.

Then from 1218 to 1220 Genghis Khan and his Mongols launched the invasion of Central Asia and destroyed the Kara-Khitan Khanate and the Khwarezmid Empire, including the splendid capital of the latter, Gurganj.The surviving Khwarezmids, fleeing Khwarezm, fled south and west in search of a new homeland.

The Ayyubid Sultanat of Egypt invited this fierce, dangerous, homeless army to settle in Palestine; they captured the city of Jerusalem from the crusaders, who had only recovered it by treaty from the Ayyubids a few years previous.The Ayyubids of Syria preferred their Christians as neighbors to this fierce horde.

The Sultan of Egypt, regretting his choice, united with those of Emessa and Damascus to drive them out.

The Khwarezmids, numbering only about twenty thousand men, were defeated them in several engagements, and the population rose against them as well.