In early Han dynasty, the administrator of an area to the east of the capital Chang'an was known as Zuo Neishi (左內史), and the region was also known by the same name.
In Western Han, the area administered 21 counties: Gaoling (高陵), Yueyang (櫟陽), Didao (翟道), Chiyang (池陽), Xiayang (夏陽), Ya (衙), Suyi (粟邑), Gukou (谷口), Lianshao (蓮勺), Fu (鄜), Pinyang (頻陽), Linjin (臨晉), Chongquan (重泉), Heyang (郃陽), Duiyu (祋祤), Wucheng (武城), Chenyang (沈陽), Huaide (褱德), Zheng (徵), Yunling (雲陵), Wannian (萬年), Changling (長陵), Yangling (陽陵) and Yunyang (雲陽).
[1] Over the course of Eastern Han dynasty, 9 counties (Yueyang, Didao, Gukou, Fu, Wucheng, Chenyang, Zheng, Yunling, Huaide) were abolished, and two more (Changling and Yangling) were transferred to the neighboring Jingzhao.
[3] It was further divided during the Northern Dynasties, and in early Sui, the remaining Pingyi Commandery was merged into Tong Prefecture (同州).
It administered 7 counties including Pingyi, Hancheng (韓城), Heyang, Chaoyi (朝邑), Chengcheng (澄城), Pucheng (蒲城), Xiagui (下邽) and Baishui (白水).