One of the sixteen Great Nations, AN.i.213 its capital being Bārāṇasī.
At the time of the Buddha, it had been absorbed into the kingdom of Kosala, and Pasenadi was king of both countries.DN.i.288 MN.ii.111 The Vinaya, Vin.i.28l however, mentions a Kāsika-rājā who sent a robe to Jīvaka. Even at this time, however, the memory of Kāsi as an independent kingdom seems to have been still fresh in men’s minds. It is very frequently mentioned as such in the Jātakas and elsewhere. Kāsi was once ruled by the Bhāratas, one of whom, Dhataraṭṭha, was its king in the time of Reṇu. DN.ii.235f. There seem to have been frequent wars between the countries of Kāsi and Kosala, victory belonging now to one, now to the other. In one such war, Dīghāti the Kosala king, was defeated by the king of Kāsi, but Dīghīti’s son Dīghāvu won back the kingdom. Vin.i.334
The traditional name of the king of Kāsi from time immemorial was evidently Brahmadatta, and references to kings of that name abound in the Jātakas. Among other kings of Kāsi mentioned is Kikī . MN.ii.49
Kāsi was evidently a great centre of trade and a most populous and prosperous country. Frequent mention is made of caravans leaving Kāsi to travel for trade. One highway went through Kāsi to Rājagaha Vin.i.212 and another to Sāvatthī. Vin.ii.10 Kāsi was famed for her silks, and Kāsi-robes were most highly esteemed as gifts. Mention is also made of the perfumes of Kāsi. AN.iii.391
Besides those already referred to, other names of places mentioned in literature as belonging to Kāsi, are Vāsabhagāma, Macchikāsaṇḍa, Kīṭāgiri and Dhammapālagāma. Kāsi and Kosala are frequently mentioned together. AN.v.59. Kāsigāma or Kāsinigama was probably the actual name of the village in Kāsi which was given by Mahākosala to his daughter when she married Bimbisāra. The village produced a revenue of one hundred thousand, and was given to the queen for her bath and perfume money. After Bimbisāra’s death, Pasenadi withdrew the gift from Ajātasattu, which act was the cause of a war between the two. Later, when Pasenadi’s daughter Vajirā was married to Ajātasattu, the village was given back as part of her dowry. SN.i.82ff.