Although the disaster of the Mongol Invasion could not, probably, have been averted, it was undoubtedly facilitated and provoked by the greed, treachery, and irresolution of 'Alá'u'd-Dín Muḥammad, King of Khwárazm. By his greed, because, as Ibnu'l-Athír observes, he had weakened or destroyed most of the neighbouring Muhammadan States to build up for him­self an unstable and unwieldy empire; so that when he fled before the Mongols, abandoning his people to their fate, no Muhammadan prince was left to unite the forces of Islám against the heathen; by his treachery, because his murder of Mongol merchants and envoys gave Chingíz Khán the best pos­sible excuse for attacking him, and thus learning the weak and defenceless condition of Persia; and by his irresolution, because at the first reverse he passed from arrogant and boastful defiance to the extreme of panic and indecision, until, about two years after his treacherous murder of the Mongol ambassador, he died, a wretched and hunted fugitive, in an island of the Caspian Sea. It needed the gallant deeds of his son Jalálu'd-Dín to save from ignominy the memory of the once mighty Empire of Khwárazm.

Another source of weakness to the resisting power fo Islám was the quarrel which had arisen between Muḥammad Khwárazmsháh and the 'Abbásid Caliph an-Náṣir, who, suspecting his too powerful vassal of coveting the very metro­polis of Baghdád, strove, after the manner of the later Caliphs, to weaken him by intrigues, and even, as hinted by Ibnu'l-Athír and explicitly stated by al-Maqrízí, encouraged the Mongols, at whose hands his posterity was destined to perish and his house to fall, to invade his territories. * The mischief appears to have begun with the discovery, on the capture of Ghazna by Khwárazmsháh, of a correspondence between the Caliph and the fallen House of Subuktigín, from which it appeared that the Caliph had been inciting them to revolt against their suzerain. Khwárazmsháh retaliated by de­nouncing the validity of the 'Abbásid title to be regarded as the pontiffs of Islám, set up a certain Sayyid as a rival claimant to their spiritual authority, and, at a time when he should have been straining every nerve to meet the storm which threatened his north-eastern frontier, undertook a futile campaign against Baghdád, whereof the disastrous issue was precipitated and accentuated by a winter of such severity as was almost unknown in those regions.

Although it appears probable that nothing could long have averted the impending calamity, its actual incidence was due to one of those “pacific missions” of which we hear so much in these days. It seemed good to Chingíz Khán to send to Utrár, an important frontier-town of Khwárazm, a company of merchants laden with the wares of his country. As to the numbers engaged in this mission, considerable difference of opinion exists: according to an-Nasawí there were four merchants only, all Muhammadans and all subjects of Khwárazmsháh; while other writers raise the number to four hundred and fifty. * These were barbarously murdered by the Governor of Utrár, with the connivance of Khwárazmsháh, who affected to believe that they were in reality Mongol spies. Thereupon Chingíz Khán despatched an embassy, consisting of two Mongols and a Turk named Bughrá, to the Court of Khwárazmsháh to protest against this wanton violation of the laws of hospitality and the comity of nations, and to demand that the Governor of Utrár should be given up to them, failing which, they added, Khwárazmsháh must prepare for war. His only answer was to kill Bughrá and send back the two Mongols, whose beards he had shaved off. Thereupon the Mongols held a quriltáy, or general assembly, at which it was decided to attack the Empire of Khwárazm.

In spite of a trifling initial success, Muḥammad Khwárazm-sháh remained inactive and remote from the point of danger, entrusting the defence of the frontier to the Governors of the threatened towns, and waiting, it is said (though perhaps only to extenuate his cowardice and irresolution) a moment which the astrologers should declare favourable for his enterprise. And while he thus waited, in the autumn of A.D. 1219, the storm burst on Transoxiana. Utrár fell after a siege of five or six months; its Governor, the murderer of the merchants, was taken alive and put to death by having molten silver poured into his eyes and ears; and the survivors of the mas­sacre which ensued were driven to Bukhárá, there to be employed against their co-religionists in the manner already described. After Úzkand and two or three other small towns had been sacked, Jand was reduced after a short siege, and plundered for nine days, but the inhabitants were, for a wonder, spared. Banákat next fell; Khujand was gallantly defended by Tímúr Malik; and in the early part of the year A.D. 1220 the Mongol hosts were masters of Bukhárá, which they plundered and burned, massacring a great number of the inhabitants, and outraging their wives, sisters, and daughters. Amongst those who, preferring death to dishonour, died fighting were the Qáḍi Badru'd-Dín, the Imám Ruknu'd-Dín, and his son. The turn of Samarqand came next; it surrendered on the fourth day of the siege, was plundered in the usual way, and a large number of its inhabitants killed or reduced to slavery.

Meanwhile Muḥammad Khwárazmsháh continued to retreat, warning the inhabitants of the towns through which he passed to do the best they could for themselves, since he could not protect them. Believing that the Mongols would not dare to cross the Oxus, he halted for a while at Níshápúr, but three weeks later, learning that they were already in Khurásán, he fled westwards to Qazwín, whence he turned back into Gílán and Mázandarán. There, being deserted by most of his followers and attacked by pleurisy, he died, a miserable and hunted fugitive, on an island in the Caspian, nominating his son, the brave Jalálu'd-Dín, as his successor. His mother, Turkán Khátún, together with his wives, children, and jewels, fell into the hands of the Mongols. Khwárazm next fell, and, irritated by the stubborn resistance which it had offered, the Mongols put to the sword nearly all the inhabitants except the artisans and craftsmen, who were transported into Mongolia. According to the author of the fámi'u't-Tawáríkh, * the besieging army numbered 50,000, and each man of them had twenty-four prisoners to kill! Amongst those who perished was the venerable and pious Najmu'd-Dín Kubrá. * The inhabitants of Tirmidh were similarly treated, and in addition, because one old woman was found to have swallowed a pearl, their corpses were eviscerated.

The bloodthirsty ferocity of the Mongols seems to have increased in proportion to their successes, and seldom indeed, from this time onwards, do we hear of any mercy shown by the Tartars to the inhabitants of the towns which they subdued. At Balkh, at Nuṣrat-Kúh, at Nasá, at Níshápúr, at Merv, and elsewhere, the same atrocious massacres in­variably followed the capture or surrender of the town. Those slain at Merv alone are computed by Ibnu'l-Athír at 700,000, but the author of the fahán-gushá raises their number to the enormous total of 1,300,000, “not counting those whose corpses remained hidden in obscure retreats.” At Níshápúr the heads of the slain were cut off, lest any living creature might be overlooked amongst them, and built into pyramids, the heads of men, women, and children being kept apart. Herát fared somewhat better, but Bámiyán, where a Mongol prince was slain in the attack, was utterly destroyed, not even spoils of war being taken, so that for a hundred years it remained a desert void of inhabitants. That nothing might be wanting to complete the ruin which they had wrought, the Mongols frequently destroyed all the grain which they did not need, and often, a few days after they had retired from a town which they had sacked, used to send a detachment to revisit its ruins and kill such poor wretches as had emerged from the hiding-places which had sheltered them from the first massacre. This happened at Merv, where 5,000 survivors of the terrible slaughter mentioned above were thus destroyed. Torture was freely used to make the vanquished disclose hidden treasure, and, as might be expected of those who held human life so cheaply, the treasures of literature and art preserved in these ancient cities were ruthlessly destroyed. Juwayní says that, in the Musulmán lands devastated by the Mongols, not one in a thousand of the inhabitants survived; and declares that even should nothing happen thereafter until the Resurrection to check the increase of population in Khurásán and 'Iráq-i-'Ajam, the population of these two provinces could never attain the tenth part of what it was before the Mongol invasion. * It was the terror of the Mongol deeds which lent such deadly meaning to their stereotyped summons to surrender which they addressed to the inhabitants of each doomed city:—“If you do not submit, how can we tell what will happen? God only knows what will happen!”*