As you have found, significant Arab and black populations in Europe are mostly (with specific exceptions such as the descendants of the Spanish Moors) a product of postwar migration flows, due to both decolonisation and increased ease of global travel.

However, there would have been a large number of Arab and black soldiers serving as colonial troops in the French Army, and it would be interesting to know whether the Germans treated them any differently to other prisoners of war. Did the Vichy government return them to North Africa, or retain them in metropolitan France?