Now that the two Yemeni states were independent, expectations rose that there would be some form of amalgamation, especially since both states publicly claimed to support the idea; such a move was not, however, forthcoming, the primary reason being the drastic divergence of political orientation that developed after the departure of all the various foreign elements from both states. Whereas the north elected to remain a market economy and retain ties with the Western states, as well as with Saudi Arabia, the south began to move rapidly in a socialist direction under the leadership of the more radical elements of the NLF.

The new southern government changed the name of the country to the People's Republic of South Yemen. Short of resources and unable to obtain any significant amounts of aid either from the Western states or from most of the Arab ones, it began to drift toward the Soviet Union, which had no Arab state in the "socialist camp" and was therefore eager to provide economic and technical assistance. By the early 1970s, South Yemen had become an avowedly Marxist state and had inaugurated a radical nationalization and "communization" of the economy and society, renaming itself the People's Democratic Republic of Yemen (PDRY).

The differences over all manner of policies led to a brief war between the two Yemens in 1972.