Sochigel (Modern Mongolian: Сочигэл, Russian: Сочихэл, Chinese (Simplifed): 速赤格勒) was either a junior wife or concubine of Yesügei, the chief of the Khamag Mongol confederation and father of Genghis Khan. Sochigel's children were Ghengis Khan's half-siblings, and included Behter and Belgutei; the latter became one of Genghis Khan's advisors.
Behter or Bekter (Mongolian: Бэхтэр; died 1180) was the son of Yesugei, chief of the Khamag Mongol, and a junior wife named Sochigel or Suchigu in some sources and Ko'agjin in others. He was also a half-brother of Genghis Khan, then known as Temujin. On the death of Yesugei, Temujin, his mother Hoelun, his siblings and two half-brothers (including Behter, Belgutei and their mother Sochigel) were abandoned by their tribe and left to fend for themselves. Living off the land, they managed to survive. However, the older half-brothers deprived 14-year-old Temujin and his brother Qasar of their spoils. Temujin and Qasar stalked and killed Behter, for which they were scolded by their mother Hoelun.
Belgutei (c. 1161 – c. 1271) was the son of Yesugei and Sochigel and half-brother to Genghis Khan. He also became general to Genghis Khan. Belgutei was considered a wise counselor and skilled diplomat, and was often used as a messenger by Genghis Khan. With Genghis Khan's blessing, Belgutei killed the champion wrestler of the Mongols, Buri Boko, by breaking his neck during a wrestling match. This was revenge for an earlier incident when Buri Boko had fought with Belgutei and slashed him with a sword. According to legend, Belgutei lived to an unusually old age. Rashid ad-Din claims he died aged 110, while the Yuanshi reports that he was still alive when Möngke Khan took the throne in 1251, making him around 90, which would make him one of the oldest men on the earth at the time.