Postal history of postage stamps of Saudi Arabia, a state on the Arabian Peninsula, the largest country in the Arab world, formerly called the Kingdom of Najd and Hejaz (until September 22, 1932). Until the mid-1920s, the Kingdoms of Hejaz and Najd were separate states, after which postage stamps for a single kingdom began to be issued in 1925. Saudi Arabia has been a member of the Universal Postal Union since 1927.