Where did the Bai (白) surname originate from in Northern China?
In Northern China, this surname originated from Henan Province and Shaanxi Province. For instance, on the Wikipedia, you would find that this surname is used by “descendants of Bai Gongsheng, the son of a crown prince of the State of Chu during the Spring and Autumn Period.”
The place where Bai Gongsheng was granted a fief is in Xi County, Xinyang City, Henan Province of nowadays. Xinyang is in the southern Henan and borders on Hubei Province and Anhui Province. Here is a picture showing the location of Xinyang City, which is represented by the red color.
This surname is also “used by the descendants of a prince named Bai, son of Duke Wu of the State of Qin.” The place where Prince Bai was granted a fief is in Yangping Town, Chencang District, Baoji City, Shaanxi Province of nowadays. Baoji is in the western Shaanxi and borders on Gansu Province. Here is a picture showing the location of Baoji City, which is also represented by the red color.