Within the Indian epic Mahabharata, Krishna was the son of the Yadava chief Vasudeva and his wife Devaki. Hence he was known as Vasudeva Krishna or Vaasudeva.
Krishna was the key political figure in overthrowing Kansa, the king of Surasena Kingdom. The kingdom of Surasena was the native kingdom of Yadava clans constituted by the Andhakas, Vrishnis and Bhojas. By overthrowing Kansa, Krishna re-established the old king Ugrasena on the throne and stabilized the kingdom from collapse due to factional fighting within the kingdom.
The next threat came from outside the country, from the Magadha Kingdom. The ruler of Magadha, Jarasandha, attacked Surasena many times and weakened its military. Krishna and other Yadava chiefs all tried their best to hold on. At last they had to flee from their native kingdom to the south and to the west.
Later, with the initiative of Krishna, the Yadavas who fled from Surasena formed a new kingdom called Dwaraka. Its capital was Dwaravati, a city well protected by mountains on all sides, in an island, not far from the Gujarat coast. This made it immune to attacks from land. The kingdom prospered by sea trade with seafaring kingdoms.
Krishna also established a tie-up of Yadavas with the Pandavas, a faction of Kurus, who were fighting against the established Kuru Kingdom. This tie up also benefited the Yadavas, strategically. With the help of the Pandavas they overthrew the Magadha king Jarasandha who was their biggest enemy. For this assistance, Krishna in turn helped the Pandavas to win the Kurukshetra War against the Kurus headed by Duryodhana. Thus the rule of the Pandava Yudhishthira was re-established by Krishna at Indraprastha, the modern-day Delhi.