Aden was ruled as part of British India until 1937. It then became the colony of Aden and later when the Hadramaut had been incorporated the Protectorate of South Arabia was founded.
The British promised to pull out in 1968 but long before that two nationalist groups – the National Liberation Front and the Front for the Liberation of South Yemen – began a violent internecine insurrection with the British as their targets whilst they sorted out their differences. As it happened in the end it was the NLF that attended the independence talks in Geneva.
To whom do you turn when you wish to “take a pop” at imperial colonialists? Why your “new best friends” the communists. They had been receiving help from the communists since 1963 and once the last British Unit – a Royal Engineers Airfield Squadron – left Aden in December 1969 the Marxist element of the ascendant NLF declared the country ot be the The People’s Democratic Republic of Yemen.
They promptly established even closer links with the Soviet Union, the Peoples’ Republic of China, Cuba, the Palestine Liberation Organistion and even East Germany.
As time went by each and every one of these outsiders had more or less influence on PDRY but a common theme was that Oman should be brought into the communist sphere of influence.
However once Dhofar had been declared “safe for peaceful civilian developement” in 1975 the PDRY turned back in on itself and was left with the Soviets until North and South Yemen unified in 1990.