Masjid Mazin Samail Oman 600s[56] Founded by Mazin Ben Ghadooba, who is considered to be the first Omani to adopt Islam during Muhammad's lifetime.[56] Al-Hadi Mosque Sa'dah Yemen 897 Khamis Mosque Khamis, Manama Bahrain 1000–1200 (approximate)[57] Though most of the structure is dated to the 11th or 12th century, it is popularly believed to have been founded by the Caliph Omar in the 600s.[58] Mosque in Al-Ain Al Ain United Arab Emirates 1000s (Islamic Golden Age) Possible the oldest mosque in the country.[59][60] Al Badiyah Mosque Fujairah United Arab Emirates 1400s[61] Some much earlier estimates have been proposed.