The great emperor of the world and the original forefather of all great nations of the world who belong to the Āryan and Indo-European stock. He is the son of Mahārāja Nabuṣa, and he became the emperor of the world due to his elder brother’s becoming a great and liberated saintly mystic. He ruled over the world for several thousands of years and performed many sacrifices and pious activities recorded in history, although his early youth was very lustful and full of romantic stories. He fell in love with Devayānī, the most beloved daughter of Śukrācārya. Devayānī wished to marry him, but at first he refused to accept her because of her being a daughter of a brāhmaṇa. According to śāstras, a brāhmaṇa could marry the daughter of a kṣatriya but a kṣatriya could not marry the daughter of a brāhmaṇa. They were very much cautious about varṇa-saṅkara population in the world. Śukrācārya amended this law of forbidden marriage and induced Emperor Yayāti to accept Devayānī. Devayānī had a girl friend named Śarmiṣṭhā, who also fell in love with the emperor and thus went with her friend Devayānī. Śukrācārya forbade Emperor Yayāti to call Śarmiṣṭhā into his bedroom, but Yayāti could not strictly follow his instruction. He secretly married Śarmiṣṭhā also and begot sons by her. When this was known by Devayānī, she went to her father and lodged a complaint. Yayāti was much attached to Devayānī, and when he went to his father-in-law’s place to call her, Śukrācārya was angry with him and cursed him to become impotent. Yayāti begged his father-in-law to withdraw his curse, but the sage asked Yayāti to ask youthfulness from his sons and let them become old as the condition of his becoming potent. He had five sons, two from Devayānī and three from Śarmiṣṭhā. From his five sons, namely (1) Yadu, (2) Turvasu, (3) Druhyu, (4) Anuand (5) Pūru, five famous dynasties, namely (1) the Yadu dynasty, (2) the Yavana (Turk) dynasty, (3) the Bhoja dynasty, (4) the Mleccha dynasty (Greek) and (5) the Paurava dynasty, all emanated to spread all over the world. He reached the heavenly planets by dint of his pious acts, but he fell down from there because of his self-advertisement and criticizing other great souls. After his fall, his daughter and grandson bestowed upon him their accumulated virtues, and by the help of his grandson and friend Śibi, he was again promoted to the heavenly kingdom, becoming one of the assembly members of Yamarāja, with whom he is staying as a devotee. He performed more than one thousand different sacrifices, gave in charity very liberally and was a very influential king. His majestic power was felt all over the world. His youngest son agreed to award him his youthfulness when he was troubled with lustful desires, even for one thousand years. Finally he became detached from worldly life and returned the youthfulness again to his son Pūru. He wanted to hand over the kingdom to Pūru, but his noblemen and the subjects did not agree. But when he explained to his subjects the greatness of Pūru, they agreed to accept Pūru as the King, and thus Emperor Yayāti retired from family life and left home for the forest.
Ref >> Srila Prabhupada Vani.