The history of Oman is largely a story of competition, and often conflict, between two very different entities. This duality was even symbolized by the name of the country, “Sultanate of Muscat and Oman,” until 1970. The sultanate was formed from the fusion of the Batina coastal plain and its port cities, symbolically Muscat, and the interior of the country, Oman. During most periods in the recent history of the country, only the coast has been ruled by the sultan. Even before the institution of the sultanate emerged in the 18th century, however, the coast had usually been under separate, often foreign, rule. In the interior, the ideal head of government from very early times was that of an imam, even though the office often remained vacant. At many times during Omani history, of course, one part of the country or the other imposed its control and Oman was temporarily united, but the differences between the two sections of Omani society eventually split the country into two separate states again. Even within the last decade, one of the major problems in Oman's efforts to develop has been “the traditional antithesis between the sultan residing on the coast and the inwardly oriented tribes.”