Ruyang County

Ruyang County (simplified Chinese: 汝阳县; traditional Chinese: 汝陽縣; pinyin: Rǔyáng Xiàn) is a county in the west of Henan province, China, under the jurisdiction of the prefecture-level city of Luoyang.

Ruyang County has been the site of several major discoveries of fossilized dinosaur bones, including Huanghetitan ruyangensis, which was first described in 2007.

As of 2012^[update], this county is divided to 4 towns and 9 townships.

In 1959, due to the fact that the Yihe River basin of the former Yiyang Commandery now belongs to Song County and Yichuan County (at that time, the county seat of Yiyang County was located on the northern bank of the Beiru River, a tributary of the Sha River, and close to Ruzhou), Yiyang was originally under the jurisdiction of Ruzhou. However, the name "Yiyang" was easily confused with the nearby Yiyang County due to their similar pronunciation. Therefore, the county was renamed Ruyang County, but this also caused confusion with Runan County, located along the Beiru River (a tributary of the Ru River), which was historically called "Ruyang County" during the Qing dynasty.

According to the Seventh National Population Census bulletin of Luoyang City, Henan Province, Ruyang County has a permanent resident population of 434,770 people. Males account for 50.22% of the population, females 49.78%. The age structure is as follows: 0–14 years old 27.08%, 15–59 years old 54.97%, 60 years and above 17.95%, and 65 years and above 12.64%.

Ruyang County is located in the southeastern part of Luoyang City, within the Western Henan Mountains region, situated between the Funiu Mountains and the Song Mountains. The Beiru River, a tributary of the Sha River, flows through the county. Coordinates range from 112°08′ to 112°38′ E longitude and 33°49′ to 34°21′ N latitude.

The terrain is distributed in steps from south to north. The southern part is mountainous with steep peaks, with the highest peak being Jiguan Mountain at an elevation of 1,602 meters. The central part is characterized by undulating hills, and the northern part consists of plains and hills. The lowest point is at the bottom of the Dukang River at 220 meters above sea level. The county is known as "Seven Mountains, Two Ridges, One Division Plain." The average elevation is 543 meters, with an annual precipitation of 690.3 millimeters. Major rivers include the Beiru River and Dukang River, among 22 rivers in total, which belong to the Huai River and Yellow River basins.

During the Tang dynasty, Yiyang County was established under the jurisdiction of Ruzhou. In the Five Dynasties period, it was abolished by the Later Zhou dynasty. In the early Ming dynasty, the area belonged to Song County. In the twelfth year of the Chenghua era (1476), Yiyang County was re-established by partitioning eastern Song County and western Ruzhou, under the direct jurisdiction of Ruzhou Prefecture. During the Qing dynasty and early Republican period, it remained under Ruzhou jurisdiction.