What supplies are needed for Chinese brush painting?

There are a number of things people use for traditional Chinese brush painting, however you can start out with a few basics.

A stack of rice paper, you do not need the top quality while you are practicing, but you will need quite a bit.

A couple of brushes, in a couple of sizes. Bigger is not always better, find a size you are comfortable with.

Ink (paint) start with black, you can expand into other colours as you perfect the techniques. Real ink usually comes in block form and you grind it down and add water to it. A dish for the ink and a reservoir of water will get you started.

Peace and quite. One of the more difficult things to find, this is not a "learn it all in an afternoon" kind of art, you can work at it a lifetime and always improve a bit each day.

A good instructor, there are some Excellent books or maybe you could enroll in a class.

Practice. That's up to you.