During the post-classical time period, many civilizations became thriving empires, including the Islamic Caliphates and the Incan Empire. Although they peaked at different times, both the Islamic Caliphates and the Incan Empire rose quickly by means of expansion through military conquest, although the Caliphates influence was more of a religious aspect. They also differed in the use and significance of the environment around them, which further affected the way they spread and rose. Expansion was a key prominence for both the Islamic Caliphates and the Incan Empire. After the death of Muhammad, the Caliphates had their minds set on new land; expansion for them became very rapid. Fighting was not the original idea, but "holy war" was justified
