The Ottoman Empire consisted, first, of a great body of lands which were directly administered according to a system that was exceedingly intricate but approximately uniform; second, of a number of regions less directly administered under special regulations; third, of numerous tributary provinces; and fourth, of certain protected or vassal states. Outside the whole, except where the frontiers were natural, lay a belt of neutral or disputed territory, which tended to be depopulated by continual raids from both sides, only less frequent and terrible in time of peace than in time of war.[41] The great significance of this belt to the Ottoman people and government was that it furnished a continuous supply of captives for the enormous slave-trade of the empire. Outside of the raided belt, again, lay the _Dar-ul harb_, or land of war, inhabited either by peoples whose religions were regarded as inferior, or by heretics, whom it was a duty to conquer, at least when practical.[42] The order in which these several regions are mentioned, an order based on progressive diminution of control, corresponds in general to an increasing distance from Constantinople. While the Ottoman Empire was growing, each sort of territory tended to absorb the next, proceeding from the center outward. These lands may be considered rapidly in the reverse order. The territory in which raiding was frequent consisted of a strip extending across Austria-Hungary from the head of the Adriatic in a northeasterly direction, and another band stretching eastwardly across Southern Poland and Russia in the edge of the forest region. The latter was separated from Crimean Tartary by the steppe land, which the Tartars kept uninhabited in order to afford a free passage to their light horse. The Persian frontier also lay waste; but the country was too much broken for easy raiding, and Mohammedans, even though heretical, could not lawfully be enslaved.[43] Similar conditions existed on the Moroccan frontier, except that the majority of the inhabitants of Morocco were orthodox Moslems. Another section that may properly be regarded as one of the raided regions from which slaves and booty were drawn was the Christian shipping on the Mediterranean Sea, and the islands and shores of that sea so far as they were held by Christians. Crimean Tartary, Georgia, Mingrelia, and parts of Arabia were vassal territories, more or less lightly attached and paying no regular tribute.[44] Venice’s island of Cyprus, the Emperor Ferdinand’s possessions in Hungary, the territories of Ragusa, Transylvania, Moldavia, and Wallachia, all paid regular tribute with occasional presents, for the privilege of maintaining their own administrations. Egypt was under a special government, adapted with slight changes from that of the Mamelukes, headed by a pasha sent out from Constantinople for a term of three years, and delivering a large part of its annual revenue to the imperial treasury. The Holy