Srimad Bhagavatam Canto 09, Chapter 18, Text 29

SB 9.18.29

pitra datta devayanyai
 sarmistha sanuga tada
svanam tat sankatam viksya
 tad-arthasya ca gauravam
devayanim paryacarat
 stri-sahasrena dasavat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Vrsaparva wisely thought that Sukracarya’s displeasure would bring danger and that his pleasure would bring material gain. Therefore he carried out Sukracarya’s order and served him like a slave. He gave his daughter Sarmistha to Devayani, and Sarmistha served Devayani like a slave, along with thousands of other women.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
In the beginning of these affairs concerning Sarmistha and Devayani, we saw that Sarmistha had many friends. Now these friends became maidservants of Devayani. When a girl married a ksatriya king, it was customary for all her girlfriends to go with her to her husband’s house. For instance, when Vasudeva married Devaki, the mother of Krsna, he married all six of her sisters, and she also had many friends who accompanied her. A king would maintain not only his wife but also the many friends and maidservants of his wife. Some of these maidservants would become pregnant and give birth to children. Such children were accepted as dasi-putra, the sons of the maidservants, and the king would maintain them. The female population is always greater than the male, but since a woman needs to be protected by a man, the king would maintain many girls, who acted either as friends or as maidservants of the queen. In the history of Krsna’s household life we find that Krsna married 16,108 wives. These were not maidservants but direct queens, and Krsna expanded Himself into 16,108 forms to maintain different establishments for each and every wife. This is not possible for ordinary men. Therefore although the kings had to maintain many, many servants and wives, not all of them had different establishments.