Animals protect their territory. Fierce tribalism has long existed. I find the idea that people could just live anywhere, back in the day, to be hard to believe

Animals protect their territory. Fierce tribalism has long existed. I find the idea that people could just live anywhere, back in the day, to be hard to believe. In some places? Sure. In "the entire world"? Not so much. Spain was invaded by the Moors, back in the day, because someone opened the gates, from the inside, for them for example.