Georgian Choral Music developed after the fourth century when Christianity came to Georgia via St. Nina. A great deal of music survives from the ninth century but the choral or choir music did not reach a significant manifestation until the 12th century. In this ritual music, three voices sing (three parts). The first voice, "mzahr," sings the melodic line. This melody may in itself have a range of a full octave, but there was never to be more than a 10th separating the three voices. The lowest voice, "bami," is rhythmically identical with the "mzahr" but the middle voice, "zir," was rhythmically independent of the other two.