Why Kings Had Concubines?

Its purpose was to ensure male heirs. For example, the son of an Imperial concubine often had a chance of becoming emperor.

Why did emperors have so many concubines?

An Emperor could have as many or as few concubines as he wished, with the main purpose of bearing him lots of children. During the earlier dynasties, concubines were frequently chosen from poor families and so often parents obliged, assuming that their daughters were embarking on a better life inside the palace.

How many concubines did Kings have?

He had seven hundred wives of royal birth and three hundred concubines, and his wives led him astray. As Solomon grew old, his wives turned his heart after other gods, and his heart was not fully devoted to the LORD his God, as the heart of David his father had been.