Khurasan before the Mongols

Khurasan was governed by the Khwārazm-Shāhs, an ancient regnal title adopted by the sovereign of Khwārazm—the Achaemenid satrapy of Khorezmia: Central Asian lands east of the Caspian. Since the Black Sands (Qara-Qum) desert occupies space between the Caspian Sea and the Oxus River (Amū Daryā, Jayhūn), and the Red Sands (Qizil-Qum) desert does the same between the Aral Sea and Jaxartes River (Syr Daryā, Sayhūn), settlements tended to be located along the banks of the Oxus and Jaxartes.

Khwārazm-Shāhs acquired territories from the fragmented empire of the Great Seljuqs of Persia (r. 431–552/1040–1157) and the Ghurids—the Shansabānī dynasty from the highlands of eastern Persia (r. from before c. 401/1011 to c. 610/1213). They wrested Transoxiana from the Qara Khitai/Xi Liao (r.c. 1141–1218), a dynasty straddling China and the Islamic world. The Khwārazm-Shāh and Chingiz Khan had, in effect, divided the territories of the Qara Khitai between themselves. The Khwārazm-Shāh’s domains at the cusp of the 615/1218 Mongol invasions were extensive and wealthy, and linguistically and ethnically heterogeneous. His realm included Bukhara and Samarqand, and Balkh, Herat, Marw, and Nishapur in Khurasan.

Sultan ʿAlāʾ al-Dīn (Abū al-Fatḥ) Muḥammad (r. 596–617/1200–21), the penultimate Khwārazm-Shāh, incurred the wrath of Chingiz Khan (d. 1227) through gross provocations. In 615/1218, a merchant caravan from Mongolia to the “Silk Road” oasis town of Utrār (east of the Jaxartes, 195 km/121 miles northwest of Tashkent), was plundered and the merchants massacred by a Khorezmian governor. ʿAlāʾ al-Dīn’s culpability is uncertain. Rather than apologizing to Chingiz Khan and executing his subordinate, ʿAlāʾ al-Dīn exacerbated the crisis by executing a Mongol ambassador, and shaving the beards of two ambassadors to humiliate them, thereby affronting Chingiz Khan. The breach of the steppe tradition of the inviolability of envoys terminated Chingiz’s quest for a diplomatic solution. He had shown remarkable restraint, but was pushed into war by ʿAlāʾ al-Dīn Khwārazm-Shāh.

The Mongol Irruptions

Chingiz Khan mobilized his armies in 615/1218. After consolidating his control in Mongolia, from c. 1205 he had followed the nomadic practice of attacking Chinese states.