all of the various tibetan mahāmudrā lineages originated with the mahasiddhas of the pala empire of 8-12th century india. the earliest figure is the tenth century poet yogi saraha, and his student nagarjuna (not to be confused with the earlier philosopher). saraha's collections of poems and songs, mostly composed in the apabhramsa language are the earliest indian sources for mahāmudrā teachings, aside from the buddhist tantras.