The Cambridge History of India, Vol. I: Ancient India v1.c19.s3.10

v1.c19.s3.10

As to the approximate period of these events, we see that they were supposed to have taken place not only before the time of Pasenadi, who was born about the same time as the Buddha and lived about as long, but also before the time of his father the Great Kosalan. We have four kings of Kosala mentioned as taking part in these wars, and cannot be sure that there were not others who had quieter reigns. It would be enough and more than enough to allow, in round numbers, a century for all these kings. And the period cannot be much longer than that. For the name Brahmadatta could not have been older than towards the close of the Brāhmaṇa literature; and a century and a half before the birth of the Buddha would about bring us to that.