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.
Secularism in Turkey
The establishing structure (Ruling institution of the Ottoman Empire) of the Ottoman Empire (13th century) was an Islamic state in which the head of the Ottoman state was the Sultan. The social system was organized around millet. Millet structure allowed a great degree of religious, cultural and ethnic continuity to non-Muslim populations across the subdivisions of the Ottoman Empire and at the same time it permitted their incorporation into the Ottoman administrative, economic and political system. The Ottoman-appointed governor collected taxes and provided security, while the local religious or cultural matters were left to the regional communities to decide. On the other hand, the sultans were Muslims and the laws that bound them were based on the Sharia, the body of Islamic law, as well as various cultural customs. The Sultan, beginning in 1517, was also a Caliph, the leader of all the Sunni Muslims in the world. By the turn of the 19th century the Ottoman ruling elite recognized the need to restructure the legislative, military and judiciary systems to cope with their new political rivals in Europe. When the millet system started to lose its efficiency due to the rise of nationalism within its borders, the Ottoman Empire explored new ways of governing its territory composed of diverse populations.