region in east-central Yemen, on the Gulf of Aden. The region comprises a hilly area near the coast and an inland valley occupied by a seasonal watercourse, the Wadi Ḥaḍramawt, that runs parallel to the coast before turning southeastward to reach the sea. In its lower reaches this watercourse achieves a year-round flow and is called Wadi Masīlah. At higher elevations in the region, there is alluvial soil that allows for an extensive agriculture, mainly of wheat and barley; other crops include fruits, dates, alfalfa, millet, and tobacco. Al-Mukallā is the chief town and seaport; of the numerous smaller towns, many are near the watercourse. Several traditional centres of learning are in Hadhramaut, most notably in the town of Tarīm. Fish products, honey, lime, and tobacco are exported from the region. Historically, large numbers of Hadhramaut's people have immigrated to East Africa, Indonesia, and Saudi Arabia to improve their living conditions. Besides Al-Mukallā, the major towns in the region include Shibām, which has examples of multistoried tall buildings about 500 years old; Tarīm; and Al-Ghuraf and Ar-Riyān, both of which have airports.