From Chinese 赵 (zhào)
which refers to an ancient city-state in what is now Shanxi province. According to legend, King Mu rewarded his chariot driver Zaofu with the city, at which time Zaofu adopted this surname. The later historic state of Zhao, which existed from the 5th to 3rd centuries BC, was named after this city.
This was the surname of Chinese emperors of the Song dynasty.