Bedouins, nomadic Arabs who herded their sheep and camels in seasonal migrations, had long inhabited the middle part of the Arabian Peninsula. These people lived in fiercely separate clans and tribes that were frequently involved in blood feuds.
Mecca, one of such cities, grew to play a unique position in Arabia. Mecca was the site of the Kaaba, Arabia's most renowned religious sanctuary, which featured depictions of approximately 360 deities and was a popular pilgrimage destination despite being off the main long-distance commerce routes.
The Byzantine Empire, heir to the Roman world, and the Sassanid Empire, heir to the imperial traditions of Persia, were on the fringe of two established and opposing civilizations at the time.
Arab troops attacked the Byzantine and Persian Sassanid empires, the region's main powers, within a few years after Muhammad's death in 632. It was the start of a process that would quickly result in an Arab empire stretching from Spain to India, reaching both Europe and China and ruling the majority of the regions in between.
Periodic plague outbreaks devastated the urban populations of the Byzantine and Persian empires for a century or more, but the more distant and scattered Arabs of the Arabian Desert were more shielded from the disease.
The majority of conquest violence involved imperial soldiers, although people were occasionally caught up in the conflict and suffered horribly. A fight between Byzantine and Arab armies in Palestine, for example, claimed the lives of 4,000 people in 634.
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