The Byzantine Empire existed for over a thousand years, with a history spanning from the division of the Roman Empire in 395 until the Ottoman conquest of Constantinople in 1453. It was formed from the previous Eastern Roman Empire, and during its long existence, the Byzantine inhabitants were very proud to call themselves Romans.

However, many things changed during the long lifespan of the Byzantine Empire, starting with its Hellenization in the 6th century. The use of the Latin language diminished and Greek took its place, while the typical Roman culture gave way to a more Hellenistic one. The Hellenization of Byzantium was detrimental to the relationship with the Holy Roman Empire, and the Christian world from that point would be split in two. The subsequent strengthening of the Orthodox Church caused many civil wars and conflicts to arise during the centuries, which shattered and reshaped the territory time after time. By the end of the Byzantine Empire's existence, the old age had weakened both the state and church, making it an easy target for invading forces.

The most notable invaders were the the Turkish-speaking Seljuks, led through a series of battles by Kutalmishouglu Suleiman, who supported different usurpers against the Byzantine emperor. The expansion of the Seljuks was so successful that when Suleiman died, he had put all of Bithynia under his control as well as several important harbor towns along the shores on the Asian side of Bosphorus. With that accomplishment, he had managed to separate the Byzantines living in Anatolia from their emperor in Constantinople. This immediately weakened the unity of the Byzantine Empire.