In his "Traditional Music of the Lao", Terry Miller identifies five factors which helped to produce the various genres of lam in Isan: animism, Buddhism, story telling, ritual courtship and male-female competitive folksongs; these are exemplified by "lam phi fa", "an nangsue", "lam phuen" and "lam gon" (for the last two factors) respectively. Of these, "lam phi fa" and "lam phuen" are probably the oldest, while it was "mor lam gon" which was the principal ancestor of the commercial "mor lam" performed today.