In 1898-99 Britain and France agreed upon their mutual spheres of influence in northern third of Africa.[1] In the north French influence would run no further than that of a diagonal line running from the intersection of the Tropic of Cancer and the 16th meridian east to the 24th meridian east, that is, the majority of the modern Chad–Libya border.[2] To the east the frontier would continue south along the 24th meridian down to the border of the Sultanate of Darfur in the vicinity of the 15th parallel north, whereupon it would roughly follow the border between Darfur and the Wadai Sultanate.[2] The precise joining point of the 16th and 24th meridians (i.e. the modern Chad-Libya-Sudan tripoint) was affirmed at the Anglo-French Convention of 8 September 1919.[2] The AEF-Anglo-Egyptian Sudan boundary was demarcated on the ground by an Anglo-French commission in 1921-23 and the final border ratified on 21 January 1924.[2][2] In 1935 France and Italy signed a treaty which would have awarded the Aouzou Strip to Italian Libya, thus shifting the tripoint south, however this treaty was never ratified.