Emirate of Transjordan
By the late 19th century, the Ruwalla were the predominant Bedouin tribe of Wadi Sirhan. The emir of the tribe, Nuri Shalan, was a signatory of the Hadda Agreement between the Emirate of Transjordan and the Sultanate of Nejd, the precursors of modern-day Jordan and Saudi Arabia, respectively. The treaty resulted in most of Wadi Sirhan becoming part of Saudi Arabia, while Jordan retained the basin's northwestern corner around Azraq.