《汉书·传·扬雄传上》
他的先人是有周伯侨的后代，作为庶出旁支以晋的扬作为食邑，并以此为氏，不知伯侨是周的哪一支系。
其先出自有周伯侨者，以支庶初食采于晋之扬，因氏焉，不知伯侨周何别也。
His ancestors were descendants of the King Bobo Wei of the Zhou dynasty, and as a concubine, he lived in Yang in Jin and used this as his surname. It is unknown from which lineage of the King Bobo Wei his ancestors came from.