This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Islam reaches Egypt when Rashidun forces under Amr ibn al As invade Byzantine Egypt in 639, opening a campaign that reaches its conclusion in 642 with the fall of Alexandria, the province's great capital and the seat of Byzantine administration there. That fall ended Byzantine rule over Egypt outright and opened the province to Islamic rule under the same expanding caliphate that had already taken Syria a few years before.
Amr ibn al As carried the campaign himself, moving from an initial invasion into a sustained conquest of the Nile valley rather than a single decisive battle the way Syria's Yarmouk had been. Alexandria's fall in 642 was the campaign's culmination, the moment Byzantine administrative control gave way entirely to the new Rashidun government.
What changed for Islam's spread is the addition of Egypt, one of the ancient world's wealthiest and most agriculturally productive provinces, to the caliphate within roughly a decade of Muhammad's own death. Its fall alongside Syria's a few years earlier meant the eastern Mediterranean's two richest Byzantine holdings had both passed to Islamic rule in the same short span, a pattern the same forces would repeat again in Persia soon after.