Dahomey, before becoming Benin, was part of the large French West Africa colony. Dahomey issued its own stamps from the very early 1900s until 1943; after this, French West Africa stamps were used, often imprinted somewhere with ‘DAHOMEY’.
Buying Dahomey stamps is not too hard for collectors of any budget today, and can be a very fun way to approach a new collection or enhance an old one.
Note that the term ‘Dahomey’ was used in French, German, Spanish, et cetera, as well as English. This makes hunting for the stamps in online text searches quite a bit easier.