The phrase “King of the Hijaz” was a title given to the ruler who owned the Hijaz region in the west of the Arabian Peninsula, which includes holy cities such as Mecca and Medina. Among the most famous who carried this title were: * Hussein bin Ali, who declared himself King of the Hijaz in 1916. * Then Abdulaziz bin Abdul Rahman Al Saud, who became known as the King of the Hijaz after entering the Hijaz in 1925, before he unified the country and declared the establishment of the Kingdom of Saudi Arabia in 1932, and his title became: King of the Kingdom of Saudi Arabia. If your question is about a coin inscribed with “King of the Hijaz”, this may help determine that it was minted in a specific historical period, but it is necessary to see the other side and read the full inscriptions to confirm the ruler's name.