Tensions between the Jin and the Mongols had begun to escalate and Genghis Khan declares war with the Jin.
The Jin government had provided Mongol leader Genghis Khan with an excuse to invade when, in 1210, it orders him to do homage to a new Jin ruler.
Refusing, the khan has mobilized his forces, ordering Öngüd raids on the northern Jin borders.
Many members of the Öngüd, or Öngüt, a Turkic tribe active in Mongolia around the time of Genghis Khan, are Nestorian Christians.
They live in an area lining the Chinese Great Wall, in the northern part of the Ordos and territories to the northeast of it.
They apparently have two capitals, a northern one at the ruin known as Olon Sume and the another a bit to the south at a place called Koshang or Dongsheng.
They act as wardens of the marches for the Chinese Empire to the north of the province of Shanxi.
The ancestors of the Ongud were the Shatuo Turks of the Western Göktürk Khaganate.
In the seventh century, they had moved to eastern Xinjiang under the protection of the Tang Dynasty.
By the ninth century, the Shatuo were scattered over North China and modern Inner Mongolia.
A Shatuo warlord, Li, had mobilized ten thousand Shatuo cavalrymen and served the Tang as ally.
In 923, his son had defeated the rebellious dynasty and become emperor of the Later Tang Dynasty.
After the overthrow of the Li family, the Shato commanders had established the Later Jin Dynasty, the Later Han Dynasty and the Northern Han.
When the Jin Dynasty conquered North China in the twelfth century, the Shatuo were called "White Tatars".
The Jin had recruited them as auxiliaries and made them guards of the Jin frontier.
The Mongols call them Onggud (Wall or Western).
The Onguds might have been converted to Christianity by the Uyghurs.
The Öngüd chief Alakush tegin had revealed the Naiman plan to attack Genghis Khan in 1205 and had allied with the Mongols.
Genghis Khan, having earlier won over both the Turkish Öngüds, or Öngüts, and the Khitan Mongols of northern China, benefits from the Öngüd location on the Jin’s northern border and the Khitans’ desire for revenge against those who had displaced them.
Genghis Khan conducts raids deep into the areas south of the Great Wall in 1211.
Using information from captured Jin engineers knowledgeable in siege craft, he develops a plan to divide his armies and make a three-pronged attack into Liaoning and Hebei.
When Genghis invades the Jin Dynasty, Alakush tegin supports him; the khan bestows his daughter Alaqai beki on his son.
