Margen
Bir Tawil is a trapezoid of desert, about 2,060 square kilometres, wedged between Egypt and Sudan. It has no permanent population, no roads, not much of anything. And it has something extremely rare: it is one of the very few territories on Earth that no state claims.
The explanation is a colonial tangle. In 1899, the British drew the border as a straight line along the 22nd parallel. In 1902 they drew another, administrative one, that strays from the straight line. Depending on which one counts, Bir Tawil falls on one side — and the Halaib Triangle, a far larger and more valuable coastal area, on the other.
Egypt upholds the 1899 border, which gives it Halaib and leaves Bir Tawil to Sudan. Sudan upholds the 1902 line: exactly the reverse. Claiming the poor patch would mean giving up the rich one.
The result: an official no-man's-land. Not because it's disputed — because it's unwanted.