Article: Turkey
Section: The Seljuks and the Ottoman Empire

Question: When did the Ottomans conquer the Byzantine Emprire?

The "House of Seljuk" was a branch of the "Kınık" Oğuz Turks who resided on the periphery of the Muslim world, in the Yabghu Khaganate of the Oğuz confederacy, to the north of the Caspian and Aral Seas, in the 9th century.
In the 10th century, the Seljuks started migrating from their ancestral homeland into Persia, which became the administrative core of the Great Seljuk Empire.
In the latter half of the 11th century, the Seljuks began penetrating into the eastern regions of Anatolia.
In 1071, the Seljuk Turks defeated the Byzantines at the Battle of Manzikert, starting Turkification of the area; the Turkish language and Islam were introduced to Anatolia and gradually spread over the region and the slow transition from a predominantly Christian and Greek-speaking Anatolia to a predominantly Muslim and Turkish-speaking one was underway.
In 1243, the Seljuk armies were defeated by the Mongols, causing the Seljuk Empire's power to slowly disintegrate.
In its wake, one of the Turkish principalities governed by Osman I would, over the next 200 years, evolve into the Ottoman Empire, expanding throughout Anatolia, the Balkans, the Levant and North Africa.
In 1453, the Ottomans completed their conquest of the Byzantine Empire by capturing its capital, Constantinople.
In 1514, Sultan Selim I (1512–1520) successfully expanded the Empire's southern and eastern borders by defeating Shah Ismail I of the Safavid dynasty in the Battle of Chaldiran.
In 1517, Selim I expanded Ottoman rule into Algeria and Egypt, and created a naval presence in the Red Sea.
Subsequently, a competition started between the Ottoman and Portuguese empires to become the dominant sea power in the Indian Ocean, with numerous naval battles in the Red Sea, the Arabian Sea and the Persian Gulf.
The Portuguese presence in the Indian Ocean was perceived as a threat for the Ottoman monopoly over the ancient trading routes between East Asia and Western Europe (later collectively named the Silk Road).
This important monopoly was increasingly compromised following the discovery of the Cape of Good Hope by Portuguese explorer Bartolomeu Dias in 1488, which had a considerable impact on the Ottoman economy.
The Ottoman Empire's power and prestige peaked in the 16th and 17th centuries, particularly during the reign of Suleiman the Magnificent.
The empire was often at odds with the Holy Roman Empire in its steady advance towards Central Europe through the Balkans and the southern part of the Polish-Lithuanian Commonwealth.
At sea, the Ottoman Navy contended with several Holy Leagues (composed primarily of Habsburg Spain, the Republic of Genoa, the Republic of Venice, the Knights of St. John, the Papal States, the Grand Duchy of Tuscany and the Duchy of Savoy) for control of the Mediterranean Sea.
In the east, the Ottomans were occasionally at war with Safavid Persia over conflicts stemming from territorial disputes or religious differences between the 16th and 18th centuries.
From the beginning of the 19th century onwards, the Ottoman Empire began to decline.
As it gradually shrank in size, military power and wealth, many Balkan Muslims migrated to the Empire's heartland in Anatolia, along with the Circassians fleeing the Russian conquest of the Caucasus.
The decline of the Ottoman Empire led to a rise in nationalist sentiment among the various subject peoples, leading to increased ethnic tensions which occasionally burst into violence, such as the Hamidian massacres.
The Ottoman Empire entered World War I on the side of the Central Powers and was ultimately defeated.
During the war, an estimated 1,500,000 Armenians were deported and exterminated in the Armenian Genocide.
The Turkish government denies that there was an Armenian Genocide and claims that Armenians were only relocated from the eastern war zone.
Large-scale massacres were also committed against the empire's other minority groups such as the Greeks and Assyrians.
Following the Armistice of Mudros on 30 October 1918, the victorious Allied Powers sought to partition the Ottoman state through the 1920 Treaty of Sèvres.