[4] Gazelles, oryx, sand cats, and spiny-tailed lizards are just some of the desert-adapted species that survive in this extreme environment, which features everything from red dunes to deadly quicksand.

The ecoregion also includes most of the Sinai Peninsula in Egypt and the adjacent Negev desert in southern Israel.

[1] The Rub' al-Khali desert is a sedimentary basin stretching along a south-west to north-east axis across the Arabian Shelf.

[5] At an altitude of 1,000 metres (3,300 ft), rock landscapes yield to the Rub' al-Khali, a vast stretch of sand whose extreme southern point crosses the center of Yemen.

The sand overlies gravel or gypsum plains and the dunes reach maximum heights of up to 250 m (820 ft).

[citation needed] The Tuwaiq escarpment is an 800 km (500 mi) arc that includes limestone cliffs, plateaus, and canyons.

Thus clear-sky conditions with plenty of sunshine prevail over the region throughout the year, and cloudy periods are infrequent.

In extremely low-lying areas, especially along the Persian Gulf (near sea level), summer temperatures can reach 48 °C (118 °F).

[8] Native mammals include the Arabian oryx (Oryx leucoryx), sand gazelle (Gazella marica), mountain gazelle (G. gazella), Nubian ibex (Capra nubiana), Arabian wolf (Canis lupus arabs), striped hyaena (Hyaena hyaena), caracal (Caracal caracal), sand cat (Felis margarita), red fox (Vulpes vulpes), and Cape hare (Lepus capensis).

[citation needed] Threats to the ecoregion include overgrazing by livestock and feral camels and goats, wildlife poaching, and damage to vegetation by off-road driving.

In the UAE, the sand gazelle and Arabian oryx are threatened, and honey badgers, jackals, and striped hyaenas already extirpated.

[1] Saudi Arabia has established a system of reserves overseen by the National Commission for Wildlife Conservation and Development (NCWCD).