Suppose you’re the leader of the United States. Both you and the head of a rival country are interested in exploring the moon.
You don’t really know what’s there. But even so, each of you wants to control it. Instead of going to war over the matter, you agree to divide up the moon. That way each of you controls part of it.
This is actually pretty much what Spain and Portugal did after Columbus returned from his first trip across the Atlantic. Their 1494 agreement, called the Treaty of Tordesillas, was the first international treaty. (A treaty is an agreement between two countries.) It set up a north–south dividing line in what Europeans called the “New World.” Everything west of the line belonged to Spain. Everything east of the line belonged to Portugal. Both Spain and Portugal supported voyages to this “New World.” Explorers sometimes sailed for one country and sometimes for the other. But few if any considered the rights of the people already living there. Or their culture or even their lives.