The Mongolian plateau was occupied mainly by five powerful tribal confederations (khanlig): Keraites, Khamag Mongol, Naiman, Mergid, and Tatar. The Jin emperors, following a policy of divide and rule, encouraged disputes among the tribes, especially between the Tatars and Mongols, in order to keep the nomadic tribes distracted by their own battles and thereby away from the Jin. Khabul's successor was Ambaghai Khan, who was betrayed by the Tatars, handed over to the Jurchen, and executed. The Mongols retaliated by raiding the frontier, resulting in a failed Jurchen counter-attack in 1143.
Genghis Khan, National Palace Museum in Taipei, Taiwan
In 1147, the Jin somewhat changed their policy, signing a peace treaty with the Mongols and withdrawing a score of forts. The Mongols then resumed attacks on the Tatars to avenge the death of their late khan, opening a long period of active hostilities. The Jin and Tatar armies defeated the Mongols in 1161.
During the rise of the Mongol Empire in the 13th century, the usually cold, parched steppes of central Asia enjoyed their mildest, wettest conditions in more than a millennium. It is thought that as a result, a rapid increase in the number of war horses and other livestock significantly enhanced Mongol military strength.
Known during his childhood as Temujin, Genghis Khan was the son of a Mongol chieftain. When his young wife Börte was kidnapped by a rival tribe, Temujin united the nomadic, previously ever-rivaling Mongol tribes under his rule through political manipulation and military might. His most powerful allies were his father's friend, Khereid chieftain Wang Khan Toghoril, and Temujin's childhood anda (friend) Jamukha of the Jadran clan. With their help, Temujin defeated the Merkit tribe, rescued his wife Börte, and went on to defeat the Naimans and Tatars.
Genghis Khan ascended the throne in the Yeke Quriltay region in the Onan river, from the Jami' al-tawarikh.
Temujin forbade looting of his enemies without permission, and he implemented a policy of sharing spoils with his Mongol warriors and their families instead of giving it all to the aristocrats. He thus held the Khan title. These policies brought him into conflict with his uncles, who were also legitimate heirs to the throne; they regarded Temujin not as leader but merely an insolent usurper. This controversy spread to his generals and other associates, and some Mongols who had previously been allies with him broke their allegiance.
War ensued, and Temujin and the forces still loyal to him prevailed, destroying all the remaining rival tribes from 1203–1205 and bringing them under his sway. In 1206, Temujin was crowned as the Khagan of the Yekhe Mongol Ulus (Great Mongol State) at a Kurultai (general assembly/council). It was there that he assumed the title of "Genghis Khan" (universal leader) instead of one of the old tribal titles such as Gur Khan or Tayang Khan, marking the start of the Mongol Empire.
Genghis Khan introduced many innovative ways of organizing his army, dividing it into decimal subsections of arbans (10 people), zuuns (100), Mingghans (1000), and tumens (10,000). The Kheshig, or the Imperial Guard, was founded and divided into day (khorchin torghuds) and night guards (khevtuul). Genghis rewarded those who had been loyal to him and placed them in high positions, placing them as heads of army units and households, even though many of his allies had been from very low-rank clans.
Mongol Empire circa 1207
Compared to the units he gave to his loyal companions, those assigned to his own family members were quite few. He proclaimed a new law of the empire, Ikh Zasag or Yassa, and codified everything related to the everyday life and political affairs of the nomads at the time. He forbade the selling of women, theft of other's properties, fighting between the Mongols, and the hunting of animals during the breeding season.
He appointed his adopted brother Shigi-Khuthugh supreme judge (jarughachi), ordering him to keep records of the empire. In addition to laws regarding family, food, and the army, Genghis also decreed religious freedom and supported domestic and international trade. He exempted the poor and the clergy from taxation. Thus, Muslims, Buddhists, and Christians from Manchuria, North China, India, and Persia joined Genghis long before his foreign conquests. He also encouraged literacy, adopting the Uyghur script, which would form the Uyghur-Mongolian script of the empire, and he ordered the Uyghur Tatatunga, who had previously served the khan of Naimans, to instruct his sons.
Genghis quickly came into conflict with the Jin dynasty of the Jurchens and the Western Xia of the Tanguts in northern China. He also had to deal with two other powers, Tibet and Khara Khitai. Towards the west he moved into Central Asia, devastating Transoxiana and eastern Persia, then raiding into Kievan Rus' (a predecessor state of Russia, Belarus, and Ukraine) and the Caucasus.
Coronation of Ögedei Khan in 1229 as the successor of Genghis Khan. By Rashid al-Din, early 14th century.
Before his death, Genghis Khan divided his empire among his sons and immediate family, making the Mongol Empire the joint property of the entire imperial family who, along with the Mongol aristocracy, constituted the ruling class.
Genghis Khan, and the following Yuan Emperors forbade Islamic practicies like Halal butchering, forcing Mongol methods of butchering animals on Muslims, and other restrictive degrees continued. Muslims had to slaughter sheep in secret. Genghis Khan directly called Muslims and Jews "slaves", and demanded that they follow the Mongol method of eating rather than the halal method. Circumcision was also forbidden. Jews were also affected, and forbidden by the Mongols to eat Kosher. Genghis Khan arranged for the Chinese Daoist master Qiu Chuji to visit him in Afghanistan and put him in charge of all religious affairs in the Empire.
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