The Odum of Ala Igbo
Hail Biafra!
Arabs, who originate from what is now Yemen actually, were largely confined to the Arabian peninsula before Muslims united the various tribes of Arabia under Islam - following the death of Muhammad. When the Muslim Arabs had united, they simultaneously attacked the Eastern Roman Empire (Byzantium) and Persia. They conquered the Levant (modern Israel-Palestine, Syria) and Mesopotamia (Iraq) and Persia proper. Egypt was under the control of the Eastern Roman Empire so they invaded that land too.
Muslim conquest of Egypt - Wikipedia