Purana means “ancient” and thus this body of literature claimed to be authoritative, especially for the kali yuga (the present age). Scholars date their composition in three periods (300-500; 500-1000; 1000-1800). Puranas deal with both philosophical and existential issues, mostly presented through a poetic narrative. The five topics covered in the Puranas are primary and secondary creations or re-creations, genealogies of gods, kings, and heroes, and the cycles of time and history. There are eighteen major Puranas and eighteen minor Puranas. Some of the main Puranas are the Bhagavata Purana, Agni Purana, Skanda Purana, Vishnu Purana, and Padma Purana.