That's the area in Gansu, west of Longshan. Longxi in ancient times refers to the place west of Longshan (Liupanshan), and Longyou also refers to Gansu in many cases. In Qin and Han Dynasties, Longxi County was ruled by Didao (now Lintao, Gansu). Longxi County is the earliest administrative system in Gansu.

Longxi is named after Longxi. Since ancient times, it has been a "country with four blockades" and a battleground for military strategists. As early as prehistoric times, ancestors thrived on this land, leaving behind cultural sites such as Yangshao and Qijia. Longxi County was built in the thirty-fifth year of Qin Zhao Haoqi (272 BC), and Wuxiang County was built in the early Han Dynasty. The Sui Dynasty changed Longxi County, and the county name is still in use today.

At the beginning of Han Dynasty, Wu Xiang County was established. In the second year of Gaozu (the first 205 years), it belonged to Longxi County; In the second year of yuanshuo (127), it belonged to Longxi county, Liangzhou; Ding Yuan three years (former 1 14), Jiatian County, Longxi County. At that time, there were four counties in Longxi County, namely, Wu Xiang, Shouyang, Tandao and Gan Lan, which belonged to Longxi County and Tianshui County respectively, and both counties were placed under the Liangzhou Secretariat Department.

Reference: Baidu Encyclopedia Longxi