The loose Xianbei confederacy lacked the organization of the Xiongnu but was highly aggressive until the death of their khan Tanshihuai in 182. Tanshihuai's son Helian lacked his father's abilities and was killed in a raid on Beidi in 186. Helian's brother Kuitou succeeded him, but when Helian's son Qianman came of age, he challenged his uncle to succession, destroying the last vestiges of unity among the Xianbei. By 190, the Xianbei had split into three groups with Kuitou ruling in Inner Mongolia, Kebineng in northern Shanxi, and Suli and Mijia in northern Liaodong. In 205, Kuitou's brothers Budugen and Fuluohan succeeded him. After Cao Cao defeated the Wuhuan at the Battle of White Wolf Mountain in 207, Budugen and Fuluohan paid tribute to him. In 218, Fuluohan met with the Wuhuan chieftain Nengchendi to form an alliance, but Nengchendi double crossed him and called in another Xianbei khan, Kebineng, who killed Fuluohan. Budugen went to the court of Cao Wei in 224 to ask for assistance against Kebineng, but he eventually betrayed them and allied with Kebineng in 233. Kebineng killed Budugen soon afterwards.