The epic describes its own growth. It names a version called Jaya of 8,800 verses, a Bharata of 24,000, and the full Mahabharata of 100,000, a three-stage account of accretion offered by the text itself, which is unusual and which broadly matches what philology finds. Scholars generally place the process between roughly 400 BCE and 400 CE, with a heroic narrative core older still and the didactic books the latest heavy additions. Sukthankar argued for a systematic Brahmanical reworking, associated with the Bhrigu clan, that expanded the epic with law and lineage material.
Tradition holds instead that Vyasa composed it entire, dictating to Ganesha, and that its length is original. Vyasa is also the biological grandfather of both sets of cousins and intervenes in the plot repeatedly, which makes the authorship claim a narrative device as much as a bibliographic one.
Whether any war lies behind it cannot be settled. There is no inscription, no destruction layer, no securely identified Kurukshetra battlefield. Traditional chronology places the war at the start of the Kali Yuga, conventionally 3102 BCE, a date derived from astronomical calculation in later Sanskrit sources rather than from any record contemporary with the events. Archaeologists who accept a historical kernel tend to associate it with Painted Grey Ware settlements in the Ganga-Yamuna doab around 1000-900 BCE, on the basis that sites named in the epic, Hastinapura, Kurukshetra, Indraprastha, have occupation of that period. The material culture the epic describes is in any case that of a much later era than either date, since reciters furnished the story with the world they knew.
Its scale is conventionally put at about ten times the Iliad and the Odyssey combined.