In the XII century the eastern part of the Great Steppe was inhabited by various Turkic and Mongolian tribes — Keraits, Merkits, Tatars, Naimans and Mongols. To the south-east of them there was a state of Tungus-Churzhegni — Jin, which actively interfered in steppe affairs according to the principle of «Divide and rule».
The territory of Jin in 1142
Especially the Jin emperors were disturbed by the alliance of the Mongol clans Hamag Mongol uls under the hand of Khabul-hagan. The Mongols regularly made plundering attacks on the Jin.
After the death of Habul-hagan in 1148, the next ruler of the Mongols was his third cousin from the Taijiut clan, Ambagai-han. In 1156 Ambagai Khan decided to marry off his daughter to a chief of friendly Tatars. He took her to her future kin. On the way, he was captured by Tatars hostile to the Mongols. They took him to the Zhurchen emperor Wanyan Digunai.
He’s got a lot on his plate. Six years since he overthrew Emperor Wanyan Hel, introduced Chinese laws and way of life in Jin, was going to fight with the Song Empire.
Digunai ordered Ambagai’s execution. At the same time, Ambagai was given the opportunity to bid farewell to his relatives and sent word to them:
«I, the supreme leader of the Mongol people, was taken prisoner by the Tatars when I was taking my daughter to them. Let my example be a lesson to you! Now avenge me, sparing neither your fingernails nor all ten fingers, shooting with bows!»
The content of the letter does not say that Ambagai is angry with the Churchens. At the Tartars, yes. But not the Jinjin. Ambagai was executed in the Jin capital of Zhongdu. It’s likely Digunai didn’t figure it out. Tatars have persuaded him to execute the Mongol, that in steppe did not speak, that it was business of hands of Tatars.
Khabul-Kagan’s son Hutula Khan became the new ruler of the Mongols. He tried to take revenge on the Tatars. But in 1161 the Jinians sent troops to the steppe, which with the help of the Tatars defeated the Mongols. The Mongol alliance broke up.
Even before the war with the Tatars, the grandson of Khabul-khagan — Esugei-bagatur met in the steppe merkit Eke-Chileda and his bride Oelun. According to the traditional version it was a chance meeting. But most likely it was an ambush. Its purpose was to prevent the marriage of Oelun from the Mongol tribe Olkhonut of the Kungirat branch with the Mongol enemies Merkits. Chiledu was the younger brother of the Merkit chief Tokhtoa-beki, who twice opposed the Mongols and was defeated.
Yesugei-baatur (c. 1134 — c. 1171) — the father of Temujin-Chinggis Khan. The leader of a large part of the Mongol tribes. In «The Hidden Tale of the Mongols» Yesugei is called Baatur and Khan. Founder of the Kiyat-Borjigin family — Wikipedia
Be that as it may, Yesugei repulsed Oelun. Apparently, the girl did not want to run away with her husband, although she could have done so. Perhaps she had an arrangement with Yesugei. She became Yesugei’s eldest wife.
Oelun. Illustration from the Mongolian edition of «The Hidden Tale of the Mongols».
It should be noted that the Kiyats, to whom Esugei belonged, had long ago taken girls from the Kungirats, who were their kuda (marriage partners). The kungirats also did the same. Therefore, probably marriage of Oelun was secretly negotiated between her kin and Esugei’s kin. Openly they could not give her away, as apparently there were some obligations before Merkits.
Thus Esugei took Oelun, who had been married for ten days, as a wife. Chiledu carried her to her native nomadic village after the wedding.
Yesugei’s marriage to a Kungirat woman allowed him to become a family man. This increased Esugei’s chances of gaining supreme power from the Mongols.
Another contender was the son of Ambagai Khan — Targutai-Kiriltukh. Between him and Yesugei started a feud because of the desire for supremacy. The feud could take place even before the execution of Ambagai Khan.
Esugei’s wedding on Oelun became a catalyst of steppe war with Tatars and their allies Merkits. This war as well as all steppe wars continued with variable success until in the summer of 1162 Esugei managed to take the Tatar tribal leader Temujin-Uge captive.
At the same time the future Shaker of the Universe was born. The Tatar chief is executed, and his name was named the infant.
Nine years of childhood of the senior son of Yesugei — Temujin passed in happiness and tenderness. His father did not become Khan of the Mongols, which was caused by the intrigues of the Taijiuts led by Targutai-Kiriltukh. Yesugei also did not aspire to khan’s power, as by psychotype he was an ordinary steppe man — good-natured and lazy. It was good for Temujin, as his father devoted a lot of time to him as his firstborn and favorite.