In Numbers 12 Miriam and Aaron complained about Moses marrying a Cushite. But in Exodus 2, after he ran away to Midian, he married Reuel's daughter Zippora. That makes Zippora a Midianite, right? Are these the same woman or differnet ones? Does the bible say anything more about the Cushite?
This is a question that has caused problems with commentators and interpreters for centuries. Speaking most strictly, Cush and Midia are not the same place. Midia was on the Arabian peninsula (in the region of Jordan and Saudi Arabia today) while Cush proper was in the Sudan and Ethiopia region. In fact, the Septuagint uniformly translates Cush with Ethiopia.
In light of this, Rashbam (ca. 1085 - ca. 1158) taught that this verse was referring to a prior wife. He drew this teaching from a tradition called Yalkut Shemoni. It says that Moses fled from Egypt first to Cush (where he married and became king) then to Midia where he married Zipporah.
On the other hand, Rashi interprets this verse as Zipporah and the Cushite woman were the same. He argues that Zipporah was called "the Cushite" because of her undeniable beauty. Drawing from the question in Jeremiah 13:23 ("Can the Cushite change his skin color?"), it is understood that the Cushites have a markedly different skin color from the Israelites. And he argues that Miriam and Aaron were upset at Moses because he had separated from her for this time.
However, even though some argue the two places do not overlap, there are actually ancient traditions that the Cushites were not restricted to the Sudan.
In short, there is ample evidence that the Cushites spread beyond Ethiopia into Arabia and that Zipporah could be both Midian and Cushite.