The main visual elements are of Africa, completely black, and a very big footprint covering the whole of Africa.

This political cartoon is probably about how Africa was colonized, and that it didn't do any good, since Africa is black, "in the dark".

The cartoonist maybe wanted to say that imperialism was a "dark" time for Africa. A bad thing.

Well, Africa is coloured all in black, as if it was in the dark, and the footprint looks kind of threatening. I think it's European, because it's a footprint of a shoe, the Africans at the time probably didn't even have shoes!

Maybe the cartoonist could have had some red between the cracks in the footprint, to show that people died, and that it was a very bad time.