I asked Mr. Knorr yesterday about the Musical inspirations for both themes, and here is his reply:
The Mayan music is based on traditional Mayan music as possible. Much of their original music was lost after the arrival of the European colonizers, but I've done my best to base things off some field recordings we have of some Mayans with more limited European influence. The main theme is based on "Rabinal Achi," "Xtoles," and "Bolonchon."
For Gran Colombia, in the ancient era I've tried to include a little from some of the diverse musical styles that we find through the countries encompassing what was Gran Colombia. There is a vast and diverse number of traditions in this area as a result of the mixing of indigenous, African, and European cultures. There is some cumbia, currulao, joropo, pasillo, an Afro-Colombian spiritual, and a traditional indigenous/Colombian song included in the ancient era. The main theme for Gran Colombia includes "Velo Que Bonito," Reir Llorando," and in the medieval era "Pajarillo." I worked with Colombian instrumentalist Martin Vejarano on the music for Gran Colombia, and he plays extensively on the music for the ancient era.