Yunan County is located in the west of Guangdong Province, on the south bank of the middle reaches of Xijiang River. Xijiang River meanders eastward for 64 kilometers along the northern edge of Xun County, and the county boundary is located at 22 48'-2319' north latitude and1121'-kloc-01.
In Yunan County, the central part of the terrain is inclined to the north and south respectively, and the surface slope is steep, and the arrangement of mountains and valleys is mostly northeast-southwest trend. Jinjufeng, the highest peak in the central part of the county, is 876 meters above sea level, and the Xijiang River Valley and Nanjiang River Valley are the lowest, which is 50-60 meters. The whole terrain has no ups and downs. The county is divided into plains, terraces, terraces, hills and mountains.
The plain ground is flat or gentle, and the altitude is below 200 meters. The relative height is generally less than15m, and the composition materials are mostly Quaternary loose deposits. The soil layer is deep, the underground water content is high and humid, mainly distributed in the south bank of Xijiang River and the middle and lower reaches of Nanjiang River, Chengjian River, Guiwei River, Dahe River and Taihe River, with different widths. The area varies, with a total area of 104.44 square kilometers.
Brief introduction to the history of Yunan County:
Qin belongs to Guilin County, Han belongs to Cangwu, and Cangwu was originally a county. In the first year of Taikang in the Western Jin Dynasty (280), Duluo County (now the capital of Yunnan) and Wucheng County were placed under Duan Xi County. It is under the jurisdiction of Cangwu County.
In the 5th year of Yonghe in the Eastern Jin Dynasty (349), Jinhua County (now Nanjiangkou and Nanyao) was placed under Duan Xi County. Houduluo and Jinhua were placed under Jin Kang County (Yuanxi County, now Deqing County East).
During the Yuanjia period of the Southern Song Dynasty (424-453), Duluo and Wucheng counties merged and renamed Ducheng County (hence its name), and Ansui County (now Liantan Town, Yunnan Province) was separated from Duan Xi County. During the Southern Qi Dynasty (479-502), Weicheng County was separated from Duan Xi County, which is now a town built in Yunnan.
In the fourth year of the Southern Liang Dynasty (523), Luoyang County was established in Guluoshui (namely Wenchang Water) basin, and now part of Yunan County is included in this county. At the beginning of Sui Dynasty, Luoyang County was changed to Luoyang County.
Reference to the above content: Baidu Encyclopedia-Yunan County