Though its geographic definition may vary, the Hauran generally consists of the following subregions: the Hauran plain, which forms the heart of the region; the mountains of Jabal Hauran (also known as 'Jabal al-Druze' or 'Jabal al-Arab') east of the plain; and the Lajat volcanic field to the north of Jabal Hauran. The region is bound to the north by the Ghouta and Marj plains around Damascus and to the south by the desert steppe of Jordan. Its western boundary is marked by the Ruqqad tributary, which separates it from the Golan Heights (al-Jawlān in Arabic). It is eastwardly bound by the al-Hamad and al-Safa desert steppes. Geographer John Lewis Burckhardt, writing in 1812, defined it as follows: