What is Red Sea Nubo–Sindian tropical desert and semi-desert?

The Red Sea Nubo–Sindian tropical desert and semi-desert ecoregion covers extremely arid land along the northeastern Red Sea, the southern Sinai Peninsula, and on a thin strip along the Israel-Jordan border. Most of the coastal land is flat, but there are high mountains in southern Sinai. Biodiversity is limited by the low moisture levels - some areas go for years without significant rain. Portions of the area support a thin savannah-like cover of widely scattered trees and scrub, surrounded by grasses that briefly flourish after a rainfall. Biodiversity is highest in the mountains of Sinai, and in the wadis and gullies that retain moisture.