Upon Kaṁsa's death, his two wives became widows. According to Vedic civilization, a woman is never independent. She has three stages of life: in childhood a woman should live under the protection of her father, a youthful woman should live under the protection of her young husband, and in the event of the death of her husband she should live under the protection of her grown-up sons, or if she has no grown-up sons she must go back to her father and live as a widow under his protection. It appears that Kaṁsa had no grown-up sons. Therefore, after his wives became widows they returned to the shelter of their father. Kaṁsa had two queens, Asti and Prāpti, and both happened to be the daughters of King Jarāsandha, the lord of the Bihar Province (known in those days as Magadha). After reaching home, the two queens explained their awkward position following Kaṁsa's death. The King of Magadha, Jarāsandha, was mortified on hearing of the pitiable condition of his daughters. When informed of the death of Kaṁsa, Jarāsandha decided on the spot that he would rid the world of all the members of the Yadu dynasty. He decided that since Kṛṣṇa had killed Kaṁsa, the whole dynasty of the Yadus should be killed.
He began to make extensive arrangements to attack the kingdom of Mathurā with his innumerable military phalanxes, consisting of many thousands of chariots, horses, elephants and infantry soldiers. Jarāsandha prepared thirteen such military phalanxes to retaliate the death of Kaṁsa. Taking with him all his military strength, he attacked the capital of the Yadu kings, Mathurā, surrounding it from all directions. Śrī Kṛṣṇa, who appeared like an ordinary human being, saw the immense strength of Jarāsandha, which appeared like an ocean about to cover a beach at any moment. He also perceived that the inhabitants of Mathurā were overwhelmed with fear. He began to think within Himself about His mission as an incarnation and how to tackle the present situation before Him. He thought that since He was not going to conquer the kingdom of Magadha, to kill the King of Magadha, namely Jarāsandha, was useless. His mission was to diminish the overburdening population of the whole world; therefore He took the opportunity to face so many men, chariots, elephants and horses. The military strength of Jarāsandha had appeared before Him, and He decided to kill the entire force of Jarāsandha so that he would go back and reorganize his military strength.
While Lord Kṛṣṇa was thinking in that way, two beautiful chariots, fully equipped with drivers, weapons, flags and other paraphernalia, arrived for Him from outer space. Kṛṣṇa saw the two chariots present before Him and immediately addressed His elder brother, Balarāma, who is also known as Saṅkarṣaṇa: "My dear elder brother, best among the Āryans, You are the Lord of the universe, and, specifically, You are the protector of the Yadu dynasty. The members of the Yadu dynasty sense great danger before the soldiers of Jarāsandha, and they are very much aggrieved. Just to give them protection, Your chariot is also here, filled with weapons. I request You to sit on Your chariot and kill all these soldiers, the entire military strength of the enemy. The two of Us have descended to this earth just to annihilate such unnecessary bellicose forces and give protection to the pious devotees. So we have the opportunity to fulfill Our mission. Please let Us execute it." Thus Kṛṣṇa and Balarāma, the descendants of Daśārha, decided to annihilate the thirteen military companies of Jarāsandha.