How to create a map with customized defined regions?

Good morning,

how can I create a map with customized defined regions?

I do have a list with people, who are responsible for individual countries, but also for specifically defined regions (e.g. CEN Region)

For example:

Germany, Austria, Switzerland = DACH Region,

Belgium, Netherland, Luxembourg = BENELUX Region,

All member states of the European Union + Iceland, Norway, Switzerland + United Kingdom, North Macedonia, Turkey, Serbia = CEN Region

Thanks a lot!