http://stupidquestionarchives.blogspot.co.uk/2008/03/warpath-theme-music.html

This article gives the definitive answer. It's from a 1960's Uni. Brass band piece called "massacre" which itself is a pastiche of earlier John Ford type pastiches - which again seem to be taken from earlier Buffalo Bill Outdoor Shows.

I don't have the time to transcribe the details of the article.. but if someone has.

Apparently there is a 'chopping' gesture that many people find offensive that has gone along with the music.