So Joshua said to the people of Israel, “How long will you put off going in to take possession of the land, which the LORD, the God of your fathers, has given you?
Joshua 18:3

The assignment of land and occupation by the twelve tribes of Israel wasn't a one-time event. It was a process that took many months, probably years. Those tribes that took initiative were given the land that they captured. Tribes that failed to take initiative were assigned land. Most of life works this way. If you don't make decisions, someone else will make your decisions for you.