The Nile, flowing south to north through Egypt to the Mediterranean, is more than 4,000 miles long, by some measures the world’s longest river, though by others a few miles shorter than the Amazon River. Travelers from antiquity onward could trace it upriver as far as Khartoum in Sudan. There it splits into two feeder rivers: the Blue Nile, flowing from Lake Tana in Ethiopia and known to the West since the 17th century, and the…
