Why is the Jurchen nationality in Ming Dynasty more backward than that in Song Dynasty?

Nuzhen gives birth to Nuzhen, a mature Nuzhen

You said, "The Hong Yan Department of Jurchen became more and more powerful, and established the State of Jin. The Northern Song Dynasty occupied the Central Plains, and created its own Jurchen script based on Chinese characters, and the civilization was highly developed." Nvzhen, who moved to the Central Plains, has been feudalized. The woman who "traded ginseng and mink in the border trade market for iron in the Ming Dynasty" was really a virgin who stayed in the northeast and was still in a slave society.