All the Vedic knowledge existed before creation and is given by Lord Krishna, in His Lord Vishnu form to the first living being, Brahma, at the beginning of each cycle of creation and annihilation in each of the millions of universes. The duration of each cycle is 311.040 trillion years (311 trillion, 40 billion years). We are currently 155.522 trillion (155 trillion, 522 billion years) years into the current cycle.
The Vedic knowledge is eternal, universal, and it comes from God (Lord Krishna).
“One day of Brahma lasts one thousand cycles of four yugas [4.32 billion years]. The night is also of the same duration. At the start of Brahma’s day, all living beings become manifested from the un-manifest state. Then at night, all living beings become unmanifest again. This is repeated again, and again. At the beginning of each day of Brahma, all living beings are manifested, and at night, they are helplessly un-manifested.”(Lord Krishna, Bhagavad-Gita 8.17-19)