Oman is the only country that has a name beginning with the letter "o," as of 2014. Oman is located in the Near East, bordering the Gulf of Oman and the Arabian Sea.
Historical sovereign states that begin with the letter "o" include the Ottoman Empire and the Oyo Empire. The main portion of the Ottoman Empire was located in modern-day Turkey and collapsed in the middle of the 20th century. The Oyo Empire was located in modern-day Nigeria. The empire lost its sovereignty to the British Empire in 1888. Other historical sovereign states include Ouaddai in Central Africa, Orange Free State in Southern Africa and Oldenburg in modern-day Germany.