The question of Yemeni ‘unity’ is one of the most complex and important in modern Yemeni history. For most Yemenis, it has, since the 1950s, been an article of nationalist faith that the two Yemeni states should unite and that this could be attained in the foreseeable future. No political leadership has been able overtly to contradict this, and all political currents have sought to mobilise the popular sentiment on unity, for their own purposes. At the same time, the issue of Yemeni unity, like that of Arab unity more generally, has been a cause of considerable friction between the Yemeni states, both because of disagreements on how this unity is to be achieved and because each has used the commitment to unity as a legitimation for interference in the internal affairs of the other. The two revolutions produced states of diverging, contrasted character and each upheaval located within the other, refugee communities hostile to the orientation of the other state. The ideal of Yemeni unity is that the movement in favour of this goal can and should promote a reconciliation and fusion of the two states. The reality has been that each state, jealous of its own power, has used unity the better to strengthen its own position and contain the influence of the other.

The issue of unity has also been a source of disagreement within each of the two Yemens. In the YAR the Zeidi North has, in general, been less enthusiastic about unity than the Shafei South, whose ideological and religious orientation has been similar to that in the western part of the PDRY.