Why sub-Saharan Africa?

Sub-Saharan Africa is not only a geographical concept, but also a geopolitical feeling.

First of all, from the ethnic point of view, the people of North Africa, Egypt, Sudan, Libya, Algeria, Tunisia and Morocco (Western Sahara is a disputed area) are all Arabs, sub-Saharan Africa is all black, and Morocco is not a member of the African Union;

Secondly, from the perspective of economic and social development, the six countries in North Africa are more developed than sub-Saharan African countries (except South Africa).