Genghis Khan's eldest son was named Guest, and never escaped the doubt
Jochi's mother Börte had spent nearly nine months as a captive of the rival Merkit tribe before giving birth to him around 1182. His name meant guest in Mongolian. Genghis Khan always treated him as his own son, but his brother Chagatai never accepted it, and the quarrel cost Jochi the throne.
Börte had been betrothed to the young Temüjin at ten and married him around 1178. A few years later a Merkit raid, revenge for an old abduction by Temüjin's father, seized her from his camp, and she was forced into marriage with a Merkit man. Temüjin gathered allies under his friend Jamukha, crushed the Merkits and recovered her, heavily pregnant. The sources that record these events disagree, and most chroniclers left them out entirely.
The shadow followed Jochi. When Temüjin proposed him as husband for a daughter of his ally Toghrul, Toghrul's people took the offer as an insult, and the slight helped spark war between the two leaders. Yet after uniting the tribes and becoming Genghis Khan in 1206, the father gave Jochi the eldest son's share: nine thousand warriors with their families and herds, and the most distant lands, along the Irtysh in western Mongolia, with the expectation that he would expand them. He did, bringing the Siberian forest tribes to submit and taking over their grain, fur and gold trade.
The crisis came in 1218, as Genghis prepared to invade the Khwarazmian Empire. Asked to settle the succession, he heard Chagatai shout that he would never be ruled by a Merkit bastard. After a scuffle, the brothers agreed on the younger Ögedei as a compromise, though some historians suspect that scene was written in later. During the long, destructive siege of the Khwarazmian capital Gurganj in 1221, Jochi reportedly wanted to spare a city he expected to rule, while Chagatai did not, and Genghis handed command to Ögedei. The historian Christopher Atwood argues this version was invented to prop up Ögedei's authority.
Whatever happened, Jochi lost his father's favour, partly for failing to send Genghis his share of the spoils. He went north to his new lands, reputedly spending much time hunting, and may never have seen his father again before dying of illness around 1225. His son Batu succeeded him, founding the line that ruled the Golden Horde.
Source: Jochi
