The most credible one states that the surname Xǔ originated from the feudal state of Xǔ in the area of Xǔchāng in present-day Henan, during the Zhou Dynasty.
A different theory states that the surname originated with the fabled Xǔ You, a sage in the time of the fabled Emperor Yao, not to be confused with the later another Xǔ You who was a military strategist of the warlord Yuan Shao during the late Han Dynasty period.