Buddhist Dictionary of Pali Proper Names by G P Malalasekera
Upavatta：The sāla-grove of the Mallas of Kusināra，on the further side of the Hiraññavatī．This was the last resting-place of the Buddha on his last tour，and here he passed away，lying on a bed placed between two sāla trees （D．ii．137ff； Dpv．xv．70）．
Here Subhadda visited the Buddha in the earlier part of the last night of his life，was converted and gained admission into the Order，afterwards winning arahantship．（See also DhA．iii．377）．It was here，too，that the Buddha asked the monks if they had any doubts they wished to hear solved regarding the Buddha，the Dhamma and the Sangha，magga and patipadā，or any questions they wished to ask （A．ii．79），and here he gave his last admonition to the monks （S．i．157； see also Ud．37f）．Ananda tried to persuade him to die in a place of greater importance，and the Buddha，in order to disabuse his mind，preached to him the Mahā Sudassana Sutta （D．ii．169f）．
Buddhaghosa says （DA．ii．572f） that the road to the sāla-grove from the Hiraññavatī led from the further bank of the river，like the road from the Kadambanadī to the Thūpārāma in Anurādhapura which led through the Rājamātu-vihāra．The row of sāla-trees stretched from south to east and then continued to the north （”like the chief street in Anurādhapura”）．Hence the name Upavattana．The grove was to the southwest of Kusināra．UdA．238．