Ancient, tribal, folklore, and world music
Music existed long before mankind ever started to write it down or was even able to record it. We don’t know much about the origins of music, but it must be a concept buried deep into our hearts and brains, as we suppose that most (if not all) ancient cultures have been enjoying some kind or form of music.
Some of that music managed to survive over thousands of years, and you will be able to find information about various kinds of tribal music from all over the world. Some of that music is really ancient, but in some cases it’s also a mixture of cultural influences. Using tribal music or influences in popular music has been done many times, and it’s definitely worth giving a try (think of tribal house, or Sepultura in the 1990s for example).
And don’t forget medieval music, which has also been inspiring artists in the past. There are a few bands in Europe that mix medieval elements with hard rock or heavy metal for example, and you’ll find many bands using elements from the viking culture in scandinavian countries.
Michael Cretu’s Enigma project, a quite commercial new age dance project using gregorian chants, was also very successful in the 1990s, selling over 50 million albums.
You may check out old folklore as well, which also inspired folk music in general. Folk was very popular in the 1950s and 60s, and folk singers such as Woodrow Wilson “Woody” Guthrie influenced later icons such as Bob Dylan, Johnny Cash, and Bruce Springsteen for example.
I won’t go much into the details here, and if you plan to include such elements in your music, then you’ll have to do some research on your own.