Who were the first two empires Arab Muslims battled with?

The first two empires that Arab Muslims battled with were the Byzantine Empire and the Sassanian Empire. The conflicts began shortly after the death of the Prophet Muhammad in the early 7th century, as Muslims sought to expand their territory. Key battles like the Battle of Yarmouk in 636 against the Byzantines and the Battle of Qadisiyyah in 636 against the Sassanids marked significant victories that facilitated the rapid expansion of Islamic rule.