Several classical writers speak of him as founding an empire on the Ganges soon after the invasion of Alexander.

He was grandfather of Asoka.

Indian traditions refer to this king.
Returning to the Brahmana period, we notice that between the Sutras and Barahmanas come the Aranyakas, which are books written for the recluse.

Of these the Upanishads, before mentioned, form part.

They presuppose the existence of the Brahmanas.
Rammohun Roy was surprised that Dr.Rosen should have thought it worth while to publish the hymns of the Veda, and considered the Upanishads the only Vedic books worth reading.