Whenever the mankind suffers and is at th mercy of the tyrant, the Lord takes birth to demolish the forces of the evil. Thus, when the people of Mathura were tyranised and tortured by Kansa who threw his parents in jail and killed seven children of his sister Devaki, the Lord took birth as Krishna in the prison. And before Kansa could destroy his sister's eight child born to kill him, he was taken away to Gokhul where he was brought up as the son of Nand and Yashoda. When Kansa came to know that his enemy was growing up in Gokul, he sent one demon after another to kill him. But instead, Putana, Kaliya and all other demons were destroyed by Krishna. Ultimately Kansa sent Akrura to bring Gopal Krishna to Mathura-little knowing that he was inviting his own death!