Southern Tunisia is a region of broken terrain, with rocky ridge lines and desert, which obstruct manoeuvre; opposite a bight where the north-south coast opens to the east, a semi-arid, scrub covered coastal plain is met inland by the Matmata Hills which run south to north. North of Gabès, the road to Sfax passes between the sea and the Chotts, the only route north for the Eighth Army. Across the plain in a line roughly south-west to north-east, lay the Mareth line, a fortification built by the French in the 1930s. In the north, the hills and line of forts terminated at the Tebaga Gap, a low pass between the Matmata Hills and the Djebel Tebaga, another line of high ground to the west of the gap running east-west. North and west of this feature is the Chott el Djerid; west of the Matmata Hills, lies dry Jebel Dahar country and then the impassable sand of the Grand Erg Oriental. Gabès is on the coast where the plain meets the route from the Tebaga Gap.