Before the Han Dynasty, all male external reproductive organs were removed.

Later, it gradually developed to remove only the testicles and keep the penis.

Besides, not everyone can do this operation. It's too dangerous. You'll die if you're not careful.

So in the end, the personnel specially arranged by the court were responsible for castration.

Especially in the Ming and Qing Dynasties, penis cutting was even more rare.

Wei Zhongxian is a special case, because he castrated himself, so all the male genitals were removed.