The Uthmani Khilafah, as it was more properly called, was not actually an independant "empire" of its own, rather it was a period of Islamic history.
It was one dynasty amongst 3 major dynasties of Islamic rule, that began with the migration (Hijrah) of the Prophet
Muhammad (pbuh) and his companions from
Makkah to
Madinah. This rule was passed down between the companions of the Prophet (pbuh) until it finally landed in the hands of the Ummawi'een (
Ummayads) and was then passed through this family, until it was forcibly acquired by the Abbasi'een (
Abbasids). After the fall of
Baghdad to the Mongols in 1258 (C.E), the Abbasi'een lingered in the shadows of power, and faded into the background of the
Mamluks. Out of this situation, rose the new leadership of the Islamic World, the Uthmani'een (Ottomans).
After 150-200 years of forging their dominance over the Islamic lands, the Uthmani'een finally managed to wrest the flag of the Islamic
Khilafah from the ruins of the Abbasi'een, which had taken refuge in Egypt (Under the Mamluks). In 1520 (C.E) Ghazi Sultan Selim Khan al-Awal, recieved the bay'ah (Oath of Allegiance) from the last of the Abbasi Khulafah (Caliphs), and made official what had already been a realistic practicality for decades prior. That is, the intellectual, military and spiritual leadership over the Islamic
Ummah (Nation).
This leadership continued for 404 years, until it was finally abolished in 1924 at the hands of the Western puppet, traitor to Islam,
Mustafa Kemal (Ataturk).
At the decline of the Uthmani Khilafah, her idoelogical opponents, namely The Western powers and their agents, the Arab and Turkish nationalists, began to slander and even attack the very fabric of the Khilafah. They promoted the concept that the Turkish people were a seperate nation from the other Muslims, and that they'd only carried the flag of the Khilafah in order to subjugate and colonise the other Muslim peoples.
Today this misconception is the basis of almost all attempts to describe and document the history of the Uthmani Khilafah.
w'Allahu Alim (And God almighty knows best).