610, Angel Gabriel, an archangel, gave Muhammad the 1st Revelation from Allah (God); these revelations are in the Holy book of Islam, the Qur'an. Arabic is the language of Islam. Mecca is the holiest city, Medina is 2nd, Jerusalem is 3rd. In 632, Muhammad dies without a designated heir, leading to a split in Islam between Sunni and Shi'ite. Muhammad was a religious, political, and military leader. The Qibla Wall faces Mecca, with a mihrab (a niche). The Minbar is the pulpit for the imam (priest). Islam isn't strictly aniconic (forbidding of icons). Horror Vaccu. No images in sacred spaces. Tessellation calligraphy and arabesques. Art spread through pilgrimages. Mosques, tombs, and monuments. Islam unites a diverse region. Patrons are royal. 2D calligraphy is the highest form of art since it transmits texts revealed from God to Muhammad, making it the most respected form of art.