I believe it is Europe.
Most of the continent of Africa had been colonized by the year 1900. The African colonization was one by 7 European nations.
Africa and Asia to the extent of what i know
Asia is the most populous continent in the world, with over 4.6 billion people.
Antarctica.
At the peak of the colonial period in the early 20th century, the entire continent of Africa was colonized, every inch.
Australia.
The superlative of heavily is "most heavily."
Most of West Africa was colonized by France.
Just as with the rest of the African continent, it was colonized by the European powers for the purpose of empire (money, expansion of global influence, to "civilize" the "dark continent"). I believe Rwanda's cash crop was coffee... Germany ruled Rwanda until WW1, then the territory was handed over to Belgium, then independence from Belgium in the 1960s.
Most of West Africa was colonized by France.
The Great Depression.