Kaifeng (simplified Chinese: 开封; traditional Chinese: 開封; pinyin: Kāifēng) is a prefecture-level city in east-central Henan province, China. It is one of the Eight Ancient Capitals of China, having been the capital eight times in history, most notably during the Northern Song dynasty. As of the 2020 census, 4,824,016 people lived in Kaifeng's Prefecture, of whom 1,735,581 lived in the metropolitan area consisting of Xiangfu, Longting, Shunhe Hui, Gulou and Yuwantai Districts. Located along the Yellow River's southern bank, it borders the provincial capital of Zhengzhou to the west, Xinxiang to the northwest, Shangqiu to the east, Zhoukou to the southeast, Xuchang to the southwest, and Heze of Shandong to the northeast. Kaifeng is a major city for research in central China, ranking as the world's 138th top city by scientific output as tracked by the Nature Index. The city is home to a campus of Henan University, one of the national key universities in the Double First Class University Plan.