How did the muslims treat conquered people?

Well, I think they were allowed to practice their own religion, but they had to pay poll tax to be exempt from the military.
Hopefully, this helps!~

Muslims were tolerant conquerors for the time-period, but there was no concept of equal rights (especially since the concept of "rights" did not exist until the Enlightenment in Europe). Non-Muslims, called Dhimmi in Muslim-ruled state, lived in Muslim territories at the will of the sovereign. In this situation, they were allowed to practice their religions and cultures, but not as equals under the law. It is also important to note that polytheists such as the Zoroastrians and the Hindus were treated belligerently by their Muslim conquerors at several critical moments.The Dhimmi had to pay the jizya, or tax for not believing in Islam. Dhimmi also had to pay additional taxes on land-holdings and these taxes where called kharaj.* In addition, the Dhimmi could not sell wine or pork in the public marketplace. They were not allowed to build new places of worship, restore old places of worship, or perform any act which could be viewed as proselytization. In many jurisdictions, a Dhimmi could not trust law enforcement to protect him, a judge to accept his testimony (especially against a Muslim), and in certain cases had their children stolen by Islamic rulers to be raised as Muslims (most commonly in the Ottoman Empire's devşirme system). The Dhimmi was a humiliated second-class citizen.