The Vedas, the most ancient text in the history of Hinduism, were originated or created at the time of the beginning of the Universe. If one reads the vedas, it has been clearly stated in the holy scripture.
Yajurved 31.7, states that the Rigveda, Samaveda, Yajurveda and the Atharva Veda were created by the ultimate god, the god of creation, – the ultimate Ishwar who is omniscent or it is even believed that it was Lord Brahma who created the Vedas and that the four vedas were spoken by his four heads each.
AtharvaVeda 10.7.20 reiterates the same quote beatifully. It says that Rig veda, Sama, Yajur and the AtharvaVeda were created by the ultimate Ishwar, the God of Creation. It explicitly asks “ Which deva or lord created the Vedas? “ the answer given in the text says that the one who is controlling and maintaining the universe , is the one who created the vedas. Atharva is like the mouth of that Ishwar, Sama is like the hair on the skin, Yajur is the heart , and the Rig Veda is the Prana or the source.
In the Shatpath Brahman 18.104.22.168 states that the way a human breathes, the breath comes in and goes out, the Ishwar illuminated the world by creating the Vedas, and during the time of dissolution or pralay, the vedas won’t exist.
The Document was so enormous for the Yogi’s to understand, recite, and remember it in their mind and heart, that the sages did Tapasya to achieve their goals. They passed on their knowledge of the vedas, not in one go but in many years and generations.