By the Treaty of Jeddah, the United Kingdom recognised the sovereignty of King Abdulaziz of Saudi Arabia (pictured) over Hejaz and Nejd, which later merged to become Saudi Arabia.

The 1927 Treaty of Jeddah, formally the Treaty between His Majesty and His Majesty the King of the Hejaz and of Nejd and Its Dependencies was signed between the United Kingdom and Ibn Saud.

Abdulaziz bin Abdul Rahman Al Saud, known in the Western world as Ibn Saud, was the founder and first king of Saudi Arabia, reigning from 23 September 1932 until his death in 1953. He had ruled parts of the kingdom since 1902, having previously been Emir, Sultan, and King of Nejd, and King of Hejaz.

Hejaz is a historical region of the Arabian Peninsula that includes the majority of the western region of Saudi Arabia, covering the cities of Mecca, Medina, Jeddah, Tabuk, Yanbu, Taif and Al-Bahah. It is thus known as the "Western Province", and it is bordered in the west by the Red Sea, in the north by Jordan, in the east by the Najd, and in the south by Yemen. Its largest city is Jeddah, which is the second-largest city in Saudi Arabia, with Mecca and Medina, respectively, being the third- and fourth-largest cities in the country.

Najd is a historical region of the Arabian Peninsula that includes most of the central region of Saudi Arabia. It is roughly bounded by the Hejaz region to the west, the Nafud desert in al-Jawf to the north, ad-Dahna Desert in al-Ahsa to the east, and Rub' al-Khali to the south, although its exact boundaries cannot be determined due to varying geographical and political limits throughout history.