Greater Yemen (Arabic: اليمن الكبرى - Al-Yaman al-Kubrā) is a geographic term denoting territories of historic South Arabia which included the present territory of the Republic of Yemen as well as the Saudi regions of 'Asir, Najran, Jizan, adjacent islands in the Red Sea, adjacent parts of Tihamah and the Omani governorate of Dhofar.
Greater Yemen is also a political term denoting the irredentist aspiration that these areas be united under a common state. These claims are based on the historical notion of Bilad al-Yaman (the Land of the southern Peninsula) as well as the Rasulid state of the 13th-15th centuries and the Zaidi state of the late 17th and early 18th centuries which encompassed most of the territory of Greater Yemen.
In the 20th century, Imam Yahya Muhammad Hamid ed-Din, King of the Mutawakkilite Kingdom of Yemen (North Yemen) attempted to realize these aspirations but only managed to consolidate his control in Upper Yemen, Lower Yemen, Marib, and Lower Tihamah. He expressed his claim to Aden and the Aden Protectorate in treaties, such as in the Italo-Yemeni Treaty of 1926. He was forced to acknowledge Saudi control over Asir and was unable to dislodge the British from the Aden hinterland or Hadhramaut. British control of Aden was also challenged by his successor King Ahmad bin Yahya who did not recognise British suzerainty in South Arabia and also had ambitions of creating a unified Greater Yemen. In the late 1940s and the early 1950s, Yemen was involved in a series of border skirmishes along the disputed Violet Line, a 1913 Anglo-Ottoman demarcation that served to separate Yemen from the Aden Protectorate.
After Aden achieved independence from Britain in the 1960s, it united with North Yemen in 1990 to form the Republic of Yemen, which saw the majority of Greater Yemen ruled as a single polity for the first time in nearly two centuries, but the Southern Movement has since 1994 sought the secession of south Yemen.