Unlike the scriptorial content of the Vedas, Mahabharata is an epic and it tells a story like Illiad and Odyssey.

There are lots of debates about the actual date of authorship of Mahabharata.

But one thing is certain. Mahabharata was initially composed of 8000 verses to contain the core story of an internecine war between two cousin-clans of the Kuru dynasty. At its present form, after several renditions it grew to 100,000 verses.

Also, it must have been written after the Vedic period.