Yong Kai was a leader of the rebellion in Nanzhong against Shu Han. The Chinese Wikipedia article is titled 雍闓 and says the name is also written 雍凯; it calls him a leading chief of southern Yi Province from Yizhou commandery and a descendant of Yong Chi, a general under Emperor Gaozu of Han. Wikidata uses the same Chinese label with the English label Yong Kai and records his death in 225, so the title stays as his personal name.[2][1]
The Nanzhong revolt
Chinese Wikipedia says his ancestors were Han migrants who had lived so long in Nanzhong that they were deeply influenced by the region and 'their kindness and good faith were known across the southern lands'. In 223, the year of Liu Bei's death, Yong Kai joined Gao Ding and Zhu Bao in rebelling against Shu Han in Nanzhong. They killed the grand administrator of Yizhou, Zheng Ang, and seized his successor Zhang Yi. Li Yan wrote six letters urging him to submit, but he replied that 'the land has no second king' and resolved to rebel. Under the urging of Shi Xie and Bu Zhi he then went over to Wu and sent Zhang Yi there, and Wu made him grand administrator of Yongchang.[2]
He was held up by the resistance of Lü Kai and Wang Kang, so he sent Meng Huo to stir up the Yi and Yue peoples to rebel in support. Also involved were Zhu Bao, grand administrator of Zangke, and Gao Ding, king of the Yi of Yuesui.[2]
Death
In the spring of 225 Zhuge Liang led his army south in three columns, and Yong Kai led his men to Yuesui to help the local chief Gao Ding. Chinese Wikipedia says he was killed in the campaign against him, though another account says that, because of conflict between the great clans and the native peoples, he was killed by Gao Ding's men. The article lists the Records of the Three Kingdoms biography of Lü Kai, the Chronicles of Huayang, and the Zizhi tongjian among its references.[2]
In Romance of the Three Kingdoms
The same article says the novel's account of him is close to the histories. He is a descendant of Yong Chi and grand administrator of Jianning in Nanzhong. In chapter 87, after Liu Bei's death, he joins Zhu Bao, Gao Ding and the Man king Meng Huo in revolt and attacks Yongchang, but Zhuge Liang's divisive scheme leads to his being killed by Gao Ding's officer E Huan.[2]