Ibn Saud spent the next three decades trying to re-establish his family's rule over central Arabia, starting with his native Najd. His chief rivals were the Al Rashid clan in Ha'il, the Sharifs of Mecca in the Hijaz, and the Ottoman Turks in al-Hasa. Ibn Saud also had to contend, however, with the descendants of his late uncle Saud ibn Faisal (later known as the "Saud al-Kabir" branch of the family), who posed as the rightful heirs to the throne. Though for a time acknowledging the sovereignty of the Ottoman Sultans and even taking the title of "pasha", Ibn Saud allied himself to the British, in opposition to the Ottoman-backed Al Rashid. From 1915 to 1927, Ibn Saud's dominions were a protectorate of the British Empire, pursuant to the 1915 Treaty of Darin.