The abilities of Ibrahim, who directed the government from 1718 to 1730, preserved an unusual internal peace in the empire, though the frontier provinces were often the scenes of disorder and revolt. This was repeatedly the case in Egypt and Arabia, and still more frequently in the districts northward and eastward of the Black Sea, especially among the fierce Noghai tribes of the Kuban. The state of the countries between the Black Sea and the Caspian Sea was rendered still more unstable by the rival claims of Russia and the Porte; it was difficult to define a boundary between the two empires in pursuance of the partition treaty of 1723.