North Yemen's republic, proclaimed by Nasserist Free Officers after the 26 September 1962 coup against Imam Muhammad al-Badr; fought the Egyptian- vs Saudi-backed North Yemen Civil War against royalist forces until 1970, then developed as one of the two Yemeni states through the 1970s-80s.
United with the People's Democratic Republic of Yemen (South Yemen) on 22 May 1990 to form the unified Republic of Yemen.
Dedicated political history of exactly this republic — its 1962 formation, the civil war, and its development to the mid-1980s. Open-Library-verified exact title match.