A country occupying most of the Arabian Peninsula. Inhabited since ancient times by nomadic Semitic tribes, the region was consolidated under Muhammad, who established a theocratic state at Medina and gained control of all Arabia c. 630. After the caliphate was moved from Medina to Damascus in 661, the peninsula remained fragmented until most of it was united in the 1700s under the Saud family, who adopted the Wahhabi form of Islam. Crushed by Egyptian and Ottoman opposition in the 1800s, Saudi forces reconquered the peninsula in the early 1900s. The unified kingdom of Saudi Arabia was created in 1932 as an absolute monarchy under Wahhabi law. Oil was discovered in 1938 and soon became the mainstay of the economy. Riyadh is the capital and the largest city.