What is one reason why we know the Mali empire was connected to other far away regions of the world even before Mansa Musa’s pilgrimage to Mecca?

What would lead a historian to consider two events to have a relationship of correlation rather than causation

What event brought the us into wwii? what conflicts happened after the us entered the war? i know the first part of this question, i need with the second part.

In 150-200 words, name three advancements made by the egyptians and tell how they impacted the culture.