Son of Pururavas.

Antecedents: vishnu – Brahma – Chandra – Budha – Pururavas – Ayus.

Ayus was born to Pururavas and Menaka. Ayus and his wife Swarbhanavi had many children including Nahusha as per Mahabharata Adiparva Chapter 7 verse 24. Ayus had a lot of tapas energy as per Mahabharata Shantiparva Chapter 296 verse 15. He was a vegetarian according to Mahabharata Anushasanaparva Chapter 115 verse 59.