"It is our fault we love only the skull of beauty without knowing who she was, of what she died." -Paul Bowles When we looked at ancient music, the question came up of how do we know about ancient music. It is, after all, going extinct.
The main way is through archeology. Various idiophones (instruments that are hit or shaken) have been found suggesting some kind of ancient percussion. These instruments are always connected or related to nature in some way. Secondly, mythology gives us many stories in which drums and things like that are woven into the storyline. Lastly there exists many prehistoric cultures nowadays that still play the same percussive rhythms that they played 500 years ago.
Ancient music is repetitive, but not without reason. In fact, it is also often deceptively simple. Tribes used their music to put them into a kind of trance. This trance could be used for anything from seeing visions, to being able to walk over hot coals.
But almost always the music is used in accordance with some kind of ritual or work. Some rhythms are so sacred that they are played only once every hundred years. Ancestors believed ancient music was connected to the ancient world in some way.