Why do/did some countries have the definite article prepended to their names?

Factual Questions
1

The Sudan
The Gambia
The Ukraine

2

I meant definite article, but I can’t edit the title

3

In the case of Sudan, the name means “south” or “southern lands”. When I was in Sudan, no one used “The”.

4

I thought Sudan meant ‘black land’ as in “The land of Blacks.”

5

We did this one a few weeks ago.

Usually, it’s because the country’s name derives from a wider region. In the case of “the Ukraine” and “the Sudan,” these are actually the names of the region; the names of the countries are just “Ukraine” and “Sudan.”

6

Fixed.