Origins of the Kang (康) surname
Chinese sources record 6 separate lines of origin for the Kang (康) surname. Each is summarised below with its source.
Originated from the Ji (姬) surname
Wei Kangshu (卫康叔) was initially enfeoffed at Kangyi (康邑). After the Duke of Zhou's eastern expedition quelled the rebellion, he was relocated to govern the State of Wei (卫国), and his descendants adopted 'Kang' (康), the name of his original fief, as their surname.
Originated from the Zi (子) surname
Descendants of Song Kangwang (宋康王) adopted 'Kang' (康), his posthumous title, as their clan name, forming one branch of the Kang (康) surname.
Originated from the Mi (羋) surname
Descendants of Chu Kangwang (楚康王) adopted 'Kang' (康), his posthumous title, as their clan name, constituting another origin of the Kang (康) surname.
Originated from the Kuang (匡) surname
To observe naming taboos for Emperor Taizu of Song, Zhao Kuangyin (赵匡胤), the Kuang (匡) surname was changed to Zhu (主). Later, during the Zhenghe (政和) era, because the character 'Zhu' (主) was deemed inappropriate for subjects’ surnames, the Zhu (主) surname was changed again to Kang (康).
Sinicization of ethnic minorities’ surnames
During the process of Sinicization, members of ethnic minorities—including the Manchu (满族), Mongol (蒙古族), Hui (回族), Miao (苗族), and Yao (瑶族) peoples—adopted the Kang (康) surname.
From the Zhaowu Nine Surnames of Central Asia
The Kang (康) surname appears among the Zhaowu Nine Surnames (昭武九姓) of Central Asia, representing a Western Regions (Xiyu, 西域) non-Han surname that was sinicized into Kang (康).