Itihasas like Mahabharata and Ramayana contains many Puranas embedded in it. Hence, not all of the incidents mentioned in Itihasas are contemporary incidents. The life of the Pandavas since their military education as well as the Kurukshetra war are contemporary incidents mentioned by Vyasa in Mahabharata. But Mahabharata also contains narration of Nala & Damayanti as well as Satyavan and Savitri which are Puranas; these are added by others who lived several centuries after the life of Nala, Damayanti, Satyavan or Savitri. It is also probable that the narration about the submergence of Dwaraka, the final journey of the Pandavas, their death and Yudhisthira's mythical entry into heaven; these were narrated by a narrator who lived several centuries after the Pandavas. Some consider narrations about Pandavas birth and early days too as Puranas or as later additions.

All the Puranas like the Bhagavata_Purana, Matsya-Purana, Vishnu-Purana etc are records of pre-history.

Mahabharat and ramayana for example