Jarāsandha attacked the Yādavas in Mathurā seventeen times, and each time his armies were totally destroyed. Then, as Jarāsandha prepared to attack for the eighteenth time, a warrior named Kālayavana, who had been searching for a worthy opponent, was sent by Nārada Muni to fight the Yādavas. With thirty million soldiers Kālayavana laid siege to the Yādava capital. Lord Kṛṣṇa looked upon this attack with concern, for He knew that with Jarāsandha’s arrival imminent, there was a serious danger that the simultaneous attack of these two enemies might endanger the Yādavas. Therefore the Lord constructed a wonderful city within the sea as a safe haven for the Yādavas; then He brought them all there by His mystic power. This city was fully populated with members of all four social orders, and within it no one felt the pangs of thirst and hunger. The various demigods, headed by Indra, each offered as tribute to Lord Kṛṣṇa the same opulences they had originally obtained from Him to establish their positions of authority.