Between Egypt and Sudan there is a patch of desert, about the size of a small county, that neither country claims, and it isn’t because nobody noticed it. The British drew the border twice: a straight line along the 22nd parallel in 1899, and a crooked administrative one in 1902. Each line hands one country a stretch of Red Sea coast and the other this inland square of sand called Bir Tawil. The coast is worth about ten times as much, so Egypt holds to the first line and Sudan to the second, and the square goes to whichever line you have to give up. To claim it would be to admit the other side was right about the sea. So Bir Tawil is not ignored. It is the most carefully refused land on Earth, kept empty by two governments paying close attention to it.