Answer:
Non-believers.
Explanation:
The Muslim army was fighting with the Non-believers or Non-Muslim. Muslim army first told the Non-Muslim to accept Islam if they refused then the Muslim told them to pay taxes to the Muslim empire if they also refused it then the Muslim attack on them and captured the land by force and include the land in their empire. The Muslim army only fight with those who fight with them, they not get harm to the innocent people. This good behaviour affected the people and they accepted Islam.
