>>717311057
The word you're looking for is "navigable", and rivers don't have to connect to the ocean for civilizations to develop sailing. The Nile is infamously hard to sail through considering the 5 cataracts. And yet both the Egyptians AND the Nubians developed sailing. Piye, a Nubian, conducted the largest amphibious landing in human history until fucking D DAY and founded the 25th dynasty of Egypt. That's impressive considering Napata, his original capital, is 3 cataracts upstream of the main Egyptian heartland. Let's not forget the fact that Egypt also largely ignored the Delta and Mediterranean for most of its history. Alexander the Great founded the only major port in the Delta because the Egyptians didn't give a shit about it.

Not only that, but there were other Africans who had developed sailing. Again, Mansa Musa came to the throne because his brother took a fleet out West and never came back. So they obviously had access to boats. Otherwise how would Mansa Musa's brother have taken a fleet?