The Saudi population is characterized by a high degree of cultural homogeneity and by an equally high degree of social stratification. The territory that in 1992 constituted the Kingdom of Saudi Arabia consisted of four distinct regions and diverse populations. Each region has sustained some measure of nomadic and seminomadic population: as recently as 1950, at least one-half the total population of the kingdom was estimated to be nomadic. Tribal identities were paramount among the nomadic population and among those in towns and villages who recognized a tribal affiliation. The Eastern Province had a substantial Shia (see Glossary) population with cultural links to Iran, Bahrain, and other places in the gulf region, as well as an Indian, Yemeni, and black African component (see Shia, this ch.). Asir was more closely linked to Yemen than to Saudi Arabia both by population and geography.