[vinod2070]

It would be the invasion and utter destruction and complete devastation of the Khwarezmid Empire which would earn - and rightly - the Mongols the name for bloodthirsty ferocity that would mark the remainder of their campaigns. In this brief war, lasting less than two years, not only was a huge empire destroyed utterly, but Genghis Khan introduced the world to tactics that would not be seen again until the Germans used them so well in World War II - indirect attack, and complete and utter terror and slaughter of populations wholesale as weapons of war.

As usual, the artisans were sent back to Mongolia, the young women and children were given to the Mongol soldiers as slaves, and the rest of the population was massacred. The Persian scholar Juvayni states that 50,000 Mongol soldiers were given the task of executing twenty-four Urgench citizens each, which would mean that 1.2 million people were killed. While this is almost certainly exaggeration, the sacking of Urgench is considered one of the bloodiest massacres in human history.

The garrison at Merv was only about 12,000 men, and the city was inundated with refugees from eastern Khwarezmid. For six days, Tolui besieged the city, and on the seventh day, he assaulted the city. However, the garrison beat back the assault and launched their own counter-attack against the Mongols. The garrison force was similarly forced back into the city. The next day, the city's governor surrendered the city on Tolui's promise that the lives of the citizens would be spared. As soon as the city was handed over, however, Tolui reneged on his promise and slaughtered almost every person who surrendered, in a massacre possibly on a greater scale than that at Urgench. After finishing off Merv, Tolui headed westwards, attacking the cities of Nishapur and Herat. Nishapur fell after only three days and Tolui put every living thing in city, including the cats and dogs, to the sword. After Nishapur's fall, Herat surrendered without a fight. By spring 1221, the province of Khurasan was under complete Mongol rule. Leaving garrison forces behind him, Tolui headed back east to rejoin his father.