A country inhabited by the Kosalans, to the north-west of Māgadha and next to Kāsī. It is mentioned second in the list of sixteen Great Nations.AN.i.213 AN.iv.252 In the Buddha’s time it was a powerful kingdom ruled over by Pasenadi, who was succeeded by his son Viḍūḍabha. By this time Kāsī was under the subjection of Kosala. With the capture of Kāsi the power of Kosala increased rapidly, until a struggle between this country and Māgadha became inevitable. Quite soon after Bimbisāra’s death there were many fierce fights between Ajātasattu, his successor, and Pasenadi, these fights bringing varying fortunes to the combatants. The Sutta Nipāta Snp.405 AN.i.276 speaks of the Buddha’s birthplace as belonging to the Kosalans. Elsewhere. MN.ii.124 Pasenadi is reported as saying, that both the Buddha and he were Kosalans.
At the time of the Buddha Sāvatthī was the capital of Kosala. Next in importance was Sāketa. There was also Ayojjha, on the banks of the Sarayu.
Other Kosala rivers mentioned in the books are the Aciravatī DN.i.235 and the Sundarikā, SN.i.167 Snp.p.97 which is sometimes called Bāhukā. MN.i.39
Among localities spoken of as being in Kosala are Icchānaṅgala, AN.iii.30 AN.iii.341 AN.iv.340 Ukkaṭṭha, DN.i.87 Ekasālā, SN.i.111 Opasāda, MN.ii.164 Kesaputta of the Kālāmas, AN.i.188 Candalakappa, MN.ii.209 Toraṇavatthu, SN.iv.374 Dandakappa, AN.iii.402 Nagaravinda, MN.iii.290 Naḷakapāna, AN.v.122 MN.i.462 Nāḷandā, SN.iv.322 Pankadhā, AN.i.236 Venāgapura, AN.i.180 Veḷudvāra, SN.v.352 Sālā, MN.i.285 MN.i.400 SN.v.227 Sālāvatika,, DN.i.244 and Setavya. DN.ii.316
The Buddha spent the greater part of his time in Kosala, either in Sāvatthī or in touring in the various parts of the country, and many of the Vinaya rules were formulated in Kosala.
Kosala is often mentioned in combination with Kāsi in the compound Kāsi-Kosala; Pasenadi was king of Kāsi-Kosala. AN.v.59
A Pacceka Buddha, mentioned in a list of names. MN.iii.70