From west to east, the country has three regions: in the west is the coastal plain, separated from the interior by the Yabal Ansariyya, a double mountain range with a number of valleys; the centre, comprising a rugged plateau with several volcanic peaks and crossed from north-east to south-west by a range comprising various formations – Yabal Abd al-Aziz, Yabal Visir, Yabal Buwayda, Yabal Saar, Yabal al Sarqi and Yabal Garbi; and the eastern region comprising the Euphrates valley. The latter is the country’s main river, from east to north-west. Also important are its tributary Jabur and the Orontes river in the west. In the northeast corner, the frontier with Turkey is formed by the Tigris.
The biomes present in Syria, from north-west to south-east, are Mediterranean woodlands, pasturelands and desert. According to WWF, the Mediterranean woodlands comprise two ecoregions by altitude: the eastern Mediterranean low woodlands, and the montane woodlands of southern Anatolia in mountainous areas. The pasturelands and desert correspond respectively to ecoregions called Far East steppe and Mesopotamian shrubland desert.