Yayāti (ययाति), is a king in Hindu tradition. He is described to be a Chandravamsha king. He is regarded to be the progenitor of the races of the Yadavas and the Pandavas.
He is considered in some texts to the son of King Nahusha, and his wife, Ashokasundari, daughter of Shiva and Parvati; however, early sources state that Virajas, daughter of Ajyapas, was the mother of Yayati. He had five brothers: Yati, Samyati, Ayati, Viyati, and Kriti. Yayāti had conquered the whole world and was the Chakravarti ("Universal Monarch" or "World Emperor").
He married Devayani, the daughter of Shukra, and also took Sharmishtha, daughter of king Vrishaparvan, and the maid of Devayani, as his mistress. Upon hearing of his relationship with Sharmishtha, Devayani complained to her father, who in turn cursed Yayāti to old age in the prime of life, but later allowed him to exchange it with his son, Puru. His story finds mention in the Mahabharata's Adi Parva, as well as in the Bhagavata Purana and the Matsya Purana.
Brahma's son was Atri, a Brahmarshi. Atri's son was Chandra, the moon god. Chandra lent his name to the Lunar dynasty (Chandravaṃśa). Chandra's son was Budha. Budha had a son with Vaivasvaita Manu's daughter, Ila. Ila's son was Pururavas, who studied under Sage Kashyapa. Pururavas married the apsara Urvashi and had many sons, of whom Ayus was the eldest. Ayus completed his education from Sage Chyavana and married the asura princess Prabha. Ayus's son was Nahusha, who was educated by the Sage Vashistha.
Upon Indra's loss of power, the devas asked Nahusha to be the new Indra. Nahusha ruled over the three worlds with the guidance of Sage Brihaspati for 100 years. Nahusha's sons, headed by Yati and Yayāti, were educated by thousands of Brahmarshis and the devas who used to wait upon their father. Nahusha eventually became arrogant, and was punished severely, as he was cursed by the saptrishi (seven sages) to be snake and to live further in Naraka (Hell). Indra was once more reinstated as the king of the devas.