He was a pupil of Vyasa, from whom he learned the Jaya, the original 8,800 verses of the Mahabharata. He later expanded the Jaya to 24,000 verses under the name Bharata, which he recited to King Janamejaya at his sarpa satra (snake sacrifice). The Harivamsa is also said to have been recited by him. The full 100,000 verses of the Mahabharata was not complete until several centuries later.
^Britannica Online Encyclopedia, article:Taxila. "The great Indian epic Mahabharata was, according to tradition, first recited at Taxila at the great snake sacrifice of King Janamejaya, one of the heroes of the story."
^Raychaudhuri, H.C. (1972). Political History of Ancient India: From the Accession of Parikshit to the Extinction of the Gupta Dynasty, Calcutta: University of Calcutta, p.38