Ottoman Empire
Several historians such as British historian Edward Gibbon and the Greek historian Dimitri Kitzikis have argued that after the fall of Constantinople, the Ottoman state took over the machinery of the Roman state, and that in essence the Ottoman Empire was a continuation of the Eastern Roman Empire under a thin Turkish Islamic guise. Kitzikis called the Ottoman state "a Greek-Turkish condominium". The American historian Speros Vryonis wrote that the Ottoman state was centered on "a Byzantine-Balkan base with a veneer of the Turkish language and the Islamic religion". Other historians have followed the lead of the Austrian historian Paul Wittek who emphasized the Islamic character of the Ottoman state, seeing the Ottoman state as a "Jihad state" dedicated to expanding the world of Islam. Another group of historians led by the Turkish historian M. Fuat Koprulu championed the ""gazi" thesis" that saw the Ottoman state as a continuation of the way of life of the nomadic Turkic tribes who had come from East Asia to Anatolia via Central Asia and the Middle East on a much larger scale, and argued that the most important cultural influences on the Ottoman state came from Persia. More recently, the American historian Heath Lowry called the Ottoman state a "predatory confederacy" led in equal parts by Turks and Greeks converted to Islam.
Ottoman Empire
By the end of Suleiman's reign, the Empire spanned approximately , extending over three continents. In addition, the Empire became a dominant naval force, controlling much of the Mediterranean Sea. By this time, the Ottoman Empire was a major part of the European political sphere. The Ottomans became involved in multi-continental religious wars when Spain and Portugal were united under the Iberian Union, the Ottomans as holders of the Caliph title, meaning leader of all Muslims worldwide, and Iberians, as leaders of the Christian crusaders, were locked in a worldwide conflict, with zones of operations in the Mediterranean sea and Indian Ocean where Iberians circumnavigated Africa to reach India, and in the way, wage wars upon the Ottomans and it's local Muslim allies and likewise the Iberians passed through newly Christianised Latin-America and had sent expeditions that traversed the Pacific in order to the Christianize formerly Muslim Philippines and use it as a base to further attack the Muslims in the far east. In which case, the Ottomans sent armies to aid its easternmost vassal and territory, the Sultanate of Aceh in Southeast Asia. During 1600s the worldwide conflict between the Ottoman Caliphate and Iberian Union was a stalement since both powers where at similar population, technology and economic levels. Nevertheless, the success of the Ottoman political and military establishment was compared to the Roman Empire, by the likes of Italian scholar Francesco Sansovino and the French political philosopher Jean Bodin.