Exceptionally qualified daughters of powerful kings were allowed to make a choice of their own bridegrooms in open competition, and such ceremonies were called svayamvara, or personal selection of the bridegroom
SB Canto 1
The children of these ladies are Pradyumna, Sāmba, Amba, etc: Ladies like Rukmiṇī, Satyabhāmā and Jāmbavatī were forcibly taken away by Him from their svayaṁvara ceremonies after He defeated many powerful kings, headed by Śiśupāla. And other ladies were also forcibly taken away by Him after He killed Bhaumāsura and thousands of his assistants. All of these ladies are glorious.
Exceptionally qualified daughters of powerful kings were allowed to make a choice of their own bridegrooms in open competition, and such ceremonies were called svayaṁvara, or personal selection of the bridegroom. Because the svayaṁvara was an open competition between the rival and valiant princes, such princes were invited by the father of the princess, and usually there were regular fights between the invited princely order in a sporting spirit. But it so happened that sometimes the belligerent princes were killed in such marriage-fighting, and the victorious prince was offered the trophy princess for whom so many princes died. Rukmiṇī, the principal queen of Lord Kṛṣṇa, was the daughter of the King of Vidarbha, who wished that his qualified and beautiful daughter be given away to Lord Kṛṣṇa. But her eldest brother wanted her to be given away to King Śiśupāla, who happened to be a cousin of Kṛṣṇa. So there was open competition, and as usual Lord Kṛṣṇa emerged successful, after harassing Śiśupāla and other princes by His unrivalled prowess. Rukmiṇī had ten sons, like Pradyumna. There were other queens also taken away by Lord Kṛṣṇa in a similar way. Full description of this beautiful booty of Lord Kṛṣṇa will be given in the Tenth Canto. There were 16,100 beautiful girls who were daughters of many kings and were forcibly stolen by Bhaumāsura, who kept them captive for his carnal desire. These girls prayed piteously to Lord Kṛṣṇa for their deliverance, and the merciful Lord, called by their fervent prayer, released them all by fighting and killing Bhaumāsura. All these captive princesses were then accepted by the Lord as His wives, although in the estimation of society they were all fallen girls. The all-powerful Lord Kṛṣṇa accepted the humble prayers of these girls and married them with the adoration of queens. So altogether Lord Kṛṣṇa had 16,108 queens at Dvārakā, and in each of them He begot ten children. All these children grew up, and each had as many children as the father. The aggregate of the family numbered 10,000,000.