A mountain district in Ceylon. King Mahācūli Mahātissa once worked in a sugar mill there for three years in order to earn money wherewith to give alms (Mhv.xxxiv.4). Near Sonnagiri was the Pipphalī-vihāra (VibhA.439).
According to the Mahāvamsatīkā (MT.624; see also Mhv.Trs.238, n.1), Sonnagiri was part of the Ambatthakola-range.