I think they didn’t. That’s more of a recent development. I’ve read beginning 2000‘s China was almost on par in semi conductors with Taiwan and US. Thanks to Chinese libs who (in opposition to Marxists) convinced the leadership, the US would never hurt their own economy so much, just to stop China from developing, China dropped the ball on semiconductors, which turned out to be a very costly mistake for China.

Stumbled upon your channel for the Chinese nuclear submarine video.