On 22 May 1990, the Yemen Arab Republic (YAR) and the People's Democratic Republic of Yemen (PDRY) carried out their old pledge to unite into a single Republic of Yemen. This historic event occurred less than three years after the YAR, seemingly secure and comfortable in its separateness, celebrated its silver jubilee in 1987. This article traces and assesses political development and socioeconomic modernization in the YAR over this more than 25-year period, and hazards some guesses on the implications of these changes for current efforts to implement Yemeni unification.The YAR, or North Yemen, as it is often called, is much more to the west than to the north of the PDRY, or South Yemen, and the two parts of Yemen together occupy the southwest corner of the Arabian Peninsula, across the Red Sea and Gulf of Aden from Ethiopia (Eritrea), Djibouti, and Somalia. North Yemen shares roughly half of its landward border with Saudi Arabia, and much of this border in the east and northeast, largely in desert areas, is undemarcated. A small portion of the equally long former border between the two Yemens, the portion nearest their intersection with Saudi Arabia in the Ramlat al-Sabatayn desert, also remained undemarcated at the time of unification.Only about the size of South Dakota or Nebraska, North Yemen is dramatically varied in geography and climate. The mountainous north-south spine of the country rises abruptly from the Red Sea coastal desert, reaching 12,000 feet at one point, and provides jagged battlements for the high plateau that stretches eastward at elevations of several thousand feet or more. These central highlands then descend very gradually to the east, ending in the sand desert beyond Marib, and more sharply to the southern uplands around the cities of Ibb and Taiz. The southern uplands and the high, rugged mountains on the western flank of the central highlands tease most of the moisture out of the seasonal monsoons, and it is in these areas that most of North Yemen's terraced agriculture and most of its more than 9 million people are found. Here most of the population lives in a few thousand widely scattered villages and tiny hamlets, and only a small percentage is concentrated in the several cities and a few dozen large towns. An even more dispersed settlement pattern prevails in the rest of the country, which is more arid and more sparsely populated.North Yemen and Afghanistan probably resemble each other more than either resembles any other late-developing country, and the resemblance is as much a