Djelfa () is the capital city of Djelfa Province, Algeria and the site of ancient city and former bishopric Fallaba, which remains a Latin catholic titular see. It has a population of 490,248 (2018 census). The city lies at the junction of the N1 and the N46 roads. Geography Djelfa is located at an elevation of 3,734 feet (1,138 m) in the Ouled Naïl Range of north-central Algeria, between the towns of Bousaada and Laghouat. It is situated in a transitional zone between the dry, steppe-like Hautes Plaines (high plateaus) of the north, characterized by chotts (intermittent salt lakes), and the Sahara to the south. The town was founded in 1852 as a French military post on a geometric plan. It serves as an important livestock market centre for the semi-nomadic Ouled Naïl confederation. Djelfa is on the 12,000 mile-long Africa Trail. The surrounding region for centuries has been the meeting place of the Ouled Naïl people, who live in black-and-red striped tents and claim descent from the Islamic prophet, Muhammad. History The area is notable for its abundance of Neolithic rock carvings dating from 7000 to 5000 BC. North of Djelfa town there is an imposing physical feature known as Rocher de Sel (English: Salt Rock) that resulted from the erosion of rock salts and marls by rain. To the west of the town Megalithic funerary structures are found. During the Roman Empire, a Roman town called Fallaba was built on the site of Djelfa. That town lasted unto late antiquity. In the 11th century, the Fatimids sent the Banu Hilal to the Tripolitania, Tunisia and Constantine areas against the Zirids. The town became an important trading post during the Hafsid era. During Philippe Pétain's period, a concentration camp was placed in Djelfa. Ecclesiastical history During the Vandal Kingdom and Roman Empire the town was the seat of an ancient bishopric. The bishopric was important enough in the Late Roman province of Numidia to become one of the many suffragan bishoprics of its Metropolitan Archbishopric in Carthage. It is possible that Christianity came to the town only after the rule of Constantine the Great, as there is no record of the bishopric under the Romans. The only known bishop of this African diocese is the Catholic bishop Salo mentioned in 484. This is considerably late compared to many of the other diocese in Numidia. Bishop Salo took part in