Liberia was also a colony. They just had the same general skin color. The map doesn’t directly say otherwise, it’s just something that tends to get ignored when you phrase it the way the map does.

It was made on land purchased by an organization literally named The American Colonization Society. It’s actually a pretty interesting era of history that’s worth looking into as while the American government declined to make it an official colony of America they did extend protectorship status that spared Liberia from the European colonization the map focuses on.

This sounds all well and good, if you don’t pay attention to the initial survival rates and don’t know that what ended up happening is the freed slaves from America ended up just running their own slave plantations, creating a system that culminated in two civil wars in the 90’s era as the majority population overthrew the rule of the families descended from the American colonizers.