Thanks to Ossi for pointing these out.
Japon - Shômyô, Chant liturgique bouddhique, Secte Tendaï
A carefully abridged representation of a mandala ceremony is sung by monks of the Tendai sect, recorded in a French studio in 1978. The music, said to maintain traditions from the 12th century, is severe but serene, rather like Gregorian chant. It is sung mainly in unison but with some elegant polyphonic sections, including one where independent melodies are sung independently.