Money is just paper (or old blue jeans, if Usa) with funny things printed on it.

It is nothing unless some people believe in it’s value. And first it needs someone who guarantees for the value.

Governments do that, by tradition. Usually they also make a rule that XY shall be the only official currency in a country.

Cryptos make an exception: it is private entities who tell people to believe in their value. And so their value is usually less stable.

If you, private xyz, invent your new “region-free” currency, you are going to have a hard time with making anyone believe in it’s value.