Re: The Prophet and “Jihad”
Arms were allows to be taken up against oppression, injustice, and aggression.
The Byzantine Empire relied on its border client states to secure its eastern frontier (Christian arab states allied to the Byzantines). These states executed Muslim emissaries and converts; Muslim armies sent to avenge these deaths were attacked by regular Byzantine military units dispatched by Constantinople to defend their allies.
The attacks by Byzantium on these Muslim armies made them a valid target for jihad
The Persian Empire, similarly, killed Muslim emissaries, as well as oppressively taxing Muslims living within its borders (Persian policy involved very heavily taxing those who lived along its western border). Both situations made Jihad permissible.