Kaifeng is the capital of the Northern Song Dynasty, and the capital is Zhao Kuangyin, Song Taizu. Kaifeng at that time was called Bianjing. The last emperor was Song Qinzong, the son of Song Huizong Zhao Zhe. After the rise of Xu Jinguo, Kaifeng was conquered. The two emperors became prisoners in Xu Jinguo and were taken to Huanglongfu (today's Acheng, Harbin), where the idiom "sit on a well and watch the sky" appeared.
After the fall of Kaifeng, the capital moved to Hangzhou (then called Lin 'an).