I remember a scene in "Martial Arts". When Donnie Yen came home, he saw Tang Wei washing fish bubbles. I don't quite understand. What was the situation then?

The master is right. It is really used to make simple condoms.

I happened to watch this movie and recalled a plot, just to express this background.

There were many ways of contraception in ancient times, even many dangerous or bizarre and ineffective ways.

Sheep intestines, animal excrement, resin, honey and so on. Without modern advancement, there is nothing we can do.