In what ways was afro-eurasia a single interacting zone, and in what respects was it a vast region of separate cultures and civilizations?

Afro-Eurasia is a solitary association zone since products could go all through the whole region and cross a ton of land/ocean, however singular traders can't move that zone alone. However Afro-Eurasia is separate societies and civic establishments in light of the fact that there was a system of trade and correspondence broadening all over the Afro-Eurasian world, and independently in parts of the Americas also gradually appeared.