The Arabs conquered Egypt from the Byzantine Empire in the mid-640s C.E.
Bulgaria was once part of the Byzantine Empire.
The Arab conquest of Byzantine Syria, Phoenicia (Lebanon), Palestine and Egypt contributed the decline of the Byzantine Empire. So did the conquest of much of what is now Turkey by the Seljuk Turks and the conquest of much of the Balkan Peninsula (southeastern Europe) by the Slavs. The Arabs and the Turks were and still are Muslims.
Through Trade and Conquest.
The main cause was the conquest by the Ottoman Turks in 1453.
Lords of Conquest happened in 1986.
Conquest of Jemtland happened in 1677.
Medieval Conquest happened in 2004.
American Conquest happened in 2003.
Conquest of Ha'il happened in 1921.
Conquest of the Desert happened in 1888.
The Krion Conquest happened in 1990.