Brahma created the fifth Veda - the Puranas and the histories - from all his mouths, since he could see all the past, present and future

Expressions researched:
"Then he created the fifth Veda" |"from all his mouths, since he could see all the past, present and future" |"the Puranas and the histories"

SB Canto 3

Then he created the fifth Veda—the Purāṇas and the histories—from all his mouths, since he could see all the past, present and future.

SB 3.12.39, Translation and Purport:

Then he created the fifth Veda—the Purāṇas and the histories—from all his mouths, since he could see all the past, present and future.

There are histories of particular countries and nations and of the world, but the Purāṇas are the histories of the universe, not only in one millennium, but in many kalpas. Brahmā has knowledge of those historical facts, and therefore all the purāṇas are histories. As originally composed by Brahmā, they are part of the Vedas and are called the fifth Veda.