Origins
Descent from Xianmen
One tradition traces the surname to descendants of the ancient fangshi Xianmen, who adopted their ancestor's epithet as their surname and honored Xianmen Zigao as the founding ancestor.
Reference: 羡姓篇 [ 百名诗人•写百家姓• 205 ]|山西|诗歌|望族|冀州|古典诗词_网易订阅
Imperial Bestowal Tradition
Another account holds that the Wanli Emperor bestowed the character Xian, meaning “having a surplus,” on an ancestor who administered government money and grain.
