So, you know how boys and girls are different, right? Well, girls have something called a uterus that can hold a baby if they decide to have one when they're older. But, every month, if they don't get pregnant, the uterus sheds some of its lining and that's what comes out of the vagina. That's what we call menstruation or "periods".
Some people believe that because women are the ones who have periods and can have babies, they were seen as very important in early societies. They were kind of like the "life-bringers" and so people started paying more attention to them and their bodies.
As people started living in groups and creating cultures, blood relations (like family and ancestry) became very important. Women could have babies and pass on their genes, so they were seen as a way to keep a family's bloodline going. In some cultures, women who couldn't have babies were seen as "less valuable" than those who could because they couldn't help continue the family's bloodline.
So, you can see how something as natural as a woman's period could have an impact on how cultures and societies developed over time. But, it's important to remember that women are not just valuable for their ability to have babies - they are valuable for who they are as individuals!