The Muslim conquests by Arab armies in the 7th century meant that most Kurds became Muslims in the 7th and 8th centuries. Most Kurds converted to Islam between the 7th and 9th centuries CE. Kurds who were not Muslim had to pay the jizya, a tax. Most of these were part of the Shafi'ite system of Islamic jurisprudence. However, although most Kurds are Muslims and part of Sunni Islam, there are also Kurds of many other religions and sects.