I had learned during my very first trip to Liberia that it was known as the Pepper Coast, but I had never heard the term "Malagueta" before I saw this historic map recently.
Malagueta peppers are now more closely associated with Brazilian cuisine, there is a popular restaurant in Astoria, Queens called Malagueta, and a lot of Brazilian, Portuguese, and even Mozambican food use melegueta peppers, which in Mozambique are called "piri-piri."
These peppers originate in the Liberia-Sierra Leone area, which for centuries (originating with the Portuguese in the mid 15th century) was known as the Malagueta Coast, as can be seen from this old Dutch map above (Cape Palmas is labelled and easy to spot, as the boundary between Malagueta (in yellow) and Guinea (in pink)--matching the Liberia-Cote D'Ivoire border of today; and Cape Mesurado and the St. Paul river, among other tributaries, are discernible). The peppers were later brought over to Brazil, and although the term Pepper Coast has survived the Anglophone colonial period (there are several companies named Pepper Coast in Monrovia), the later colonization caused the disuse of the geographical term Malagueta.
The peppers themselves, however, are easy to come across in markets throughout Liberia. And they are hot--I also learned in writing this that there is actually a measurement for the spice intensity of peppers--but if you can handle it, they are tasty.
Fiamah Market, March 2010