Lord Krishna was the eighth incarnation of the Supreme Lord, born in Mathura in Uttar Pradesh at midnight on the eighth day of the dark half of the month of Shravana, approximately five thousand years ago.
Lord Krishna was born to Vasudeva and Devaki. A sage had prophesised that their eighth child would kill Devaki's evil cousin Kansa, a demonic King and tyrant, who had forcefully taken the throne of his father, King Ugrasena, and imprisoned him. Fearful of this prophecy, he imprisoned the couple, and killed the first six sons, doubting each one of them. It appeared as if the seventh child was miscarried, but Balarama was miraculously transferred from Devaki's womb to that of Rohini, Vasudeva's youngest wife. Their eighth child then appeared to them in the form of Lord Vishnu and said He would become their son Krishna. The Lord instructed Vasudeva to exchange Him for the girl Yogamaya born to his friend Nanda and his wife Yashoda in Gokula. Vasudeva miraculously escaped from jail and carried out this instruction. Kansa tried to kill Yogamaya, thinking her to be the eighth child, but she escaped and revealed to him her identity as Durga, the personification of material energy.
For eleven years, Nanda and Yashoda were oblivious to Krishna's divine identity, or to the fact that He had been born to Devaki. Krishna was brought up amongst the cowherds, the Gopas and milkmaids, the Gopis in Gokula. Krishna had a very adventurous childhood. When Kansa learned of Krishna and Balarama's escape, he made many attempts to kill Them through a series of demons, but every time the demons were killed by Krishna. He was a mischievous yet loveable boy. He was a maestro with the flute. One of his favourite pastimes was raiding the dairies of the Gopis and mother Yashoda, stealing curds and butter, raiding orchards for fruit, and blaming the other children for his mischief! The most celebrated part of Krishna's life among the cowherds is His amorous pastimes with the Gopis, headed by His beloved Radha.
At the age of eleven, Lord Krishna went to Mathura to fulfil the prophecy and kill his uncle, Kansa, for his wicked crimes, and restored Kansa's father Ugrasena to his rightful throne. He also brought back to life His six brothers from the underworld. Thereafter He moved to Dwarka, killed many demons, married 16,108 Gopis (with Radha being His true consort) and ruled Dwarka.
When Krishna's paternal first cousins, the Pandavas, were about to commence the Mahabharata war on the Kurukshetra battlefield with their first cousins, the Kauravas, Lord Krishna spoke the Bhagavad Gita (song of God) to Arjuna (a Pandava brother) and manifested Himself to him in His universal form, Vishvarupa. Lord Krishna served as Arjuna's charioteer throughout the war, won by the Pandavas.
Sometime after the war had ended, Krishna, as well as His brother Balarama, departed from this world. That day the ocean engulfed Dwarka and the Kali Yuga commenced.