In the Yu Gong period, there were two major branches in the lower reaches of the Yellow River, the northern one was Yu Gong River (the Yellow River written in the book Yu Gong), the northeast one was one of branches of Hanzhi River (the Yellow River written in the geography chapter of Hanshu). Each of the two major branches formed a tributary system that is, the Jizhou Jiuhe and the Yanzhou Jiuhe.The Jiuhe, explained in Erya, was the Yanzhou Jiuhe and was the same as described in Hanzhi. It was located in the triangle area from Gaotang, Huanghua to Lijing. The Jizhou Jiuhe, written in Yu gGong, was located in the area from Shenxian, Huanghua to Tianjing, Rongcheng. The two different Jiuhe have been Jumbled ever since the Erya period.The disappearance of ancient Baiyangdian Lake was caused by the depositing of the silt transported by the Yu Gong Yellow River. The Yu Gong Yellow River has been choked with silt already in the later stage of the Warring States.