"Who does not know of Temujin-Chengiz Khan! I left him. He does not forgive those who dare stand before him without bowing their servile backs! He avenges the willful, he hunts down those who once fought him and slays their entire clans down to the last infant!" - A prisoner fled after the battle.
He was smart in striking a trade deal with Khorezm Shah that ultimately led to war. The strategies employed by Chengiz Khan where impeccable during 1200s. For instance, making the enemy chase a group of Tatars and later the enemies were ambushed from all sides and slaughtered, putting the captured prisoners who are physically strong in the front line of battle, exploiting weakness very quickly and exercising psychological warfare; he used to keep craftsmen alive (who used to make armory, garments, etc) and butcher rest of the people and the city. Handful of women and children were spared, so that they can spread the terror of Chengiz Khan in other places. So, when he invaded the cities, people would easily surrender. For quick mobility, all horsemen had spare horses at stations and horsemen jumped from one running horse to other along the way thereby covering long distances in short time. At night, every horseman and soldier would light five-six flame torches, which would appear to the enemy that their force was almost five times larger than it actually was!“It is not sufficient that I succeed - all others must fail.”
"At military exercises I am always in front, and in time of battle am never behind. In the space of seven years I have succeeded in accomplishing a great work, and uniting the whole world in one empire." - Chengiz Khan
"He who wishes not to cling tight to the sword's black hilt will fall victim to the sword's sharp blade!" - a saying
"All who surrender will be spared; whoever does not surrender but opposed with struggle and dissension, shall be annihilated." - Chengiz Khan, during the war with the Khwarezmian empire
"What is there in the city of scorpions and tarantulas, when there is no unity even in the face of danger?" - Jelal ed-Din Shah, mightiest son of Khorezm Shah Mohammad
According to historical study and research, Chengiz Khan's military conquests were frequently characterized by the wholesale slaughter of the vanquished. It has been estimated that his campaigns killed as many as 40 million people based on census data of the times.
"When I die, don't reveal my death in anyway. Do not weep or wail, so that the news of my death should give our enemies reason to take heart or rejoice. When the Khan and the Tangut inhabitants come through the fortress gates with gifts, pounce on them and slay them!" - lasts words of Chengiz Khan
Genghis Khan - A prolific lover: An international group of geneticists have found that nearly eight percent of the men living in the region of the former Mongol empire carry y-chromosomes that are nearly identical. That translates to 0.5 percent of the male population in the world, or roughly 16 million descendants living today. His descendants extended the empire and maintained power in the region for several hundred years, in civilizations in which harems and concubines were the norm. And the males were markedly prolific. - National Geographic News