The Federation of the Emirates of the South (Arabic: اتحاد إمارات الجنوب العربي Ittiḥād ʾImārāt al-Janūb al-ʿArabiyy) was an organization of states within the British Aden Protectorate in what would become South Yemen. The Federation of six states was inaugurated in the British Colony of Aden on 11 February 1959, and the Federation and Britain signed a “Treaty of Friendship and Protection,” which detailed plans for British financial and military assistance. It subsequently added nine states and, on 4 April 1962, became known as the Federation of South Arabia. This was joined by the Aden Colony on 18 January 1963.