In 1898-99 Britain and France agreed upon their mutual spheres of influence in northern third of Africa, and the two nations delimited a frontier between AEF and Anglo-Egyptian Sudan (i.e. the modern Chad–Sudan, CAR-Sudan and CAR-South Sudan borders).[1][2] This was followed by demarcation on the ground by an Anglo-French commission in 1921–23, with the final border being ratified on 21 January 1924.[4][3]