This is not uncommon through history everywhere. Consider that before modern times there was very little birth control and also high mortality during child birth. A man would often marry two or three times during his lifetime - not because of divorce, but because of the wife dying. Her children are left behind so the man would often remarry to have 1. a wife to raise his children 2. a wife to care for the home.

The image that comes to mind for me is so many young women in their teens that travelled to the west with pioneering families.

Finally, if you are a parent and your daughter is old enough to menstruate, she is old enough to marry. Depending upon your means, it could very well be to your benefit to marry your daughter off as soon as possible.