of the Upper Yafai tribesmen were estimated very approximately at 80,000. The area of Upper Yafa had not been visited by Europeans before Colonel M.C. Lake of the British Indian Army explored it in order to gather intelligence and to find suitable sites for landing grounds. In 1925 Lake built a small army of tribal warriors that would be able to assist the British Aden Protectorate in eventual territorial scuffles with the Imam of Yemen. Between 1955 and 1957 there were uprisings against the British authorities in Upper Yafa that were successfully suppressed. In 1959, several tribal leaders with assistance of the Mutawakkilite Kingdom of Yemen rose up against the Upper Yafa sultan. The rebellion was suppressed following bombardment by the Royal Air Force on 15, 16, and 18 June. Unlike Lower Yafa, in the 1960s Upper Yafa did not join the British-sponsored Federation of South Arabia, forming an enclave that became a part of the Protectorate of South Arabia. The Upper Yafa Sultanate was abolished in 1967 upon the founding of the People's Republic of South Yemen. South Yemen united with North Yemen in 1990 to form the Republic of Yemen. Rulers Sheikhs of Upper Yafa c.1730 - 1735 `Ali ibn Ahmad Al Harhara c.1735 - 1750 Ahmad ibn `Ali Al Harhara c.1750 - 1780 Salih I ibn Ahmad Al Harhara c.1780 - 1800 `Umar I ibn Salih Al Harhara Sultans of Upper Yafa c.1800 - 1810 Qahtan I ibn `Umar ibn Salih Al Harhara (1st time) c.1810 - 1815 `Umar II ibn Qahtan ibn `Umar Al Harhara c.1815 - 1840 Qahtan I ibn `Umar ibn Qahtan Al Harhara (2nd time) c.1840 - 1866 `Abd Allah ibn Nasir ibn Salih Al Harhara 1866 - 1875 al-Husayn ibn Abi Bakr ibn Qahtan Al Harhara 1875 - 28 Apr 1895 Muhammad I ibn `Ali ibn Salih ibn Ahmad Al Harhara 1895 - 1903 Qahtan II ibn `Umar ibn al-Husayn Al Harhara 4 Dec 1903 - 1913 Salih II ibn `Umar ibn al-Husayn Al Harhara (1st time) 1913 - 1919 `Umar III ibn Qahtan ibn `Umar Al Harhara 1919 - 1927 Salih II ibn `Umar ibn al-Husayn Al Harhara (2nd time) 1927 - 1948 Umar IV ibn Salih ibn `Umar Al Harhara 1948 - 29 Nov 1967 Muhammad II ibn Salih ibn `Umar Al Harhara Postage stamps The Sultanate of Upper Yafa issued stamps in September 1967 although Mahjaba did not have