In the womb of Tārā, Soma begot a son named Budha, who later begot in the womb of Ilā a son named Aila, or Purūravā.
Urvaśī was captivated by Purūravā’s beauty, and therefore she lived with him for some time, but when she left his company he became almost like a madman.
While travelling all over the world, he met Urvaśī again at Kurukṣetra, but she agreed to join him for only one night a year.
One year later, Purūravā saw Urvaśī at Kurukṣetra and was glad to be with her for one night, but when he thought of her leaving him again, he was overwhelmed by grief.
Urvaśī then advised Purūravā to worship the Gandharvas. Being satisfied with Purūravā, the Gandharvas gave him a woman known as Agnisthālī.
Purūravā mistook Agnisthālī for Urvaśī, but while he was wandering in the forest his misunderstanding was cleared, and he immediately gave up her company.
After returning home and meditating upon Urvaśī all night, he wanted to perform a Vedic ritualistic ceremony to satisfy his desire.
Thereafter he went to the same place where he had left Agnisthālī, and there he saw that from the womb of a śamī tree had come an aśvattha tree.
Purūravā made two sticks from this tree and thus produced a fire. By such a fire one can satisfy all lusty desires. The fire was considered the son of Purūravā.
In Satya Yuga there was only one social division, called haṁsa; there were no divisions of varṇa like brāhmaṇa, kṣatriya, vaiśya and śūdra.
The Veda was the oṁkāra.
The various demigods were not worshipped, for only the Supreme Personality of Godhead was the worshipable Deity.
Reference: Srimad Bhagwatam | Skandha 9 | Chapter 14