They are formed as borders because they are formed naturally.
To shutcho biscuit
Spain's borders do no follow rivers.
The rivers
Tigris and Euphrates Rivers.
Rivers
There are four rivers that provide natural borders for the state of Florida. They are the Flint River, the Chattahoochee River, Saint Mary's River, and the Perdido River.
lakes
The Atlantic Ocean and rivers.
because they form a natural barrier
because they follow rivers
yes it is true