Yemen has a narrow coastal plain, stretching more than 700 mi (1,130 km), along the southern edge of the Arabian peninsula. It also has interior highlands and an eastern desert. The highlands, which are actually a section of the upturned Arabian plateau, are the highest part (rising to more than 12,000 ft/3,660 m) of the Arabian peninsula. They receive an annual average rainfall of c.20 in. (50 cm), making them also the wettest part of the peninsula; most of the precipitation occurs during the summer rainy season. The remainder of Yemen is hot and virtually rainless in the coastal regions. Numerous wadis radiate from the highlands, but there are no permanent streams; oases and springs provide local water needs.
Yemen is the most populous country on the Arabian Peninsula. The population is predominantly Arab, but there are also Afro-Arabs, South Asians, and Europeans. The north of Yemen is nearly 100% Muslim, both Sunni and Zaydi Shiite; the south is predominantly Muslim, but also has Christians and Hindus. Between 1948 and 1950 about 50,000 Yemeni Jews emigrated to Israel. Arabic is the nation's principal language. The tribal social structure is still prevalent in the country, although its importance diminishes along the coast, due to more foreign contact.