>>106964018
China was poor because it was superpopulated.
Rice yields were several times lower. It was incredibly difficult to bring things from one place to another because historically China never bothered with roads outside cities, and there was little to no demand for Chinese manufactured goods after the industrialisation.
China fixed every single one of those problems alone.
The period of China being weak is called the "Century of Humiliation", which started with the Opium War and ended with the CCP. They were smart before, during and after this. It's just that the whole world bands together to fuck them up.
https://en.wikipedia.org/wiki/Century_of_humiliation