In ancient times this area was sometimes called "the middle of the world", since it was the centre of government for Yu province and lay at the heart of the Nine Provinces. During the Han Dynasty, it contributed the most officials to the central government of any commandery, and was ancestral home to the immensely influential Ru'nan Yuan clan. In former times Runan County was at various times called Ancheng County (安城县) and Ruyang County (汝阳县) amongst others. During the Zhou Dynasty (1045-256 BCE), the vassal State of Dao（道国）fell within the borders of the county.
Today Runan County falls under the jurisdiction of the prefecture level city of Zhumadian. With a land area of 1306 square kilometres the county is home to some 770,000 people (2002 figure). The county government is based in the town of Runing (汝宁镇).