Why does the world have borders ?¿

I wonder why the world has borders.
Can you imagine a world without them ?
It`s hard to picture this. You might be thinking that everythign would be better for the world; or you might think that it´s the way in which we can destroy our precious planet. I mean if you think about it, there are borders just about everywhere. Just how our dogs mark their territory, we do also. I think we make borders so that there won`t be intrusion in our personal space. It`s like not having doors in our houses or in your bathrooms and rooms. It`s uncomfortable and insecure. Everyone wants borders. I mean if you look at it this way, the romans, the egyptians, the chinese, the greeks, the indians they all had some type of borders! Yeah, since wayy back then; so maybe it`s something that comes in a sort of natruality. What we use them for is for separating territories. We then we think of: the people. We choose to name other people “illegals” even though we´re all humans. If we didn`t have borders, you would have everyhting vandilized, everything would look really different, and in bad ways.
This is why I think we have borders.