The Red Sea coastal plain is constricted throughout its length, attaining its greatest widths, 40 to 50 miles, south of Medina and south of Mecca. The name Tihāmah, used for the whole plain, is sometimes subdivided into Tihāmat Al-Ḥijāz and Tihāmat ʿAsīr.

Yemen may be divided into five major regions: a coastal plain running north-south known as the Tihāmah (an extension of the Tihāmat ʿAsīr), the western highlands, the central mountains (the Yemen Highlands), the eastern highlands, and finally the eastern and northeastern desert regions.

It is so called because of its severe heat and lack of wind, from the word At-Taham which refers to extreme heat and lack of wind.