A city in the Bhagga country, of which it was probably the capital (See, e.g., Sp.iv.862). The Buddha spent the eighth vassa there (BuA.3). Near the city was the Bhesakalávana where the Buddha stayed.
During his visits there he preached the Anumána Sutta (M.i.95f ) and the Bodhirája Sutta (M.ii.91f). The city was the residence of Nakulapítá and his wife, with whom the Buddha had several interviews. (E.g., A.ii.61; iii.295 f; iv.268; S.iii.1; iv.116).
It is said that once, when the Buddha was at Sumsumáragiri, he saw with his divine eye Moggallána at Kallaválamutta half asleep, and appeared before him and admonished him (A.iv.85).
On another occasion, he saw Anuruddha in the Veluvana in the Ceti country, pondering over the seven Mahápurisavitakkas, and appeared before him to encourage him (A.iv.228f). Both incidents show that the Buddha visited Sumsumáragiri quite early in his career, in the first year after the Enlightenment. Moggallána also stayed in Sumsumáragiri, and there Mára is said to have entered his stomach and to have given him trouble (M.i.332f.; cf. Thag.vs.1208).
Sumsumáragiri was the birthplace of Sirimanda Thera (ThagA.i.462) and the scene of the meditations of Singálakapitá.
Several Vinaya rules were passed during the Buddha's stay at Sumsumáragiri (Vin.ii.127; iv.115f; 198f).
The Dhonasákha Játaka was preached there (J.iii.157f). Prince Bodhi, the governor of the Bhagga country, evidently lived in Sumsumáragiri, and it was there that he had his famous palace, called Kokanada.
It is said (MA.i.292; SA.ii.181) that the city was so called because when it was being built a crocodile (sumsumára) made a noise in a lake near by.