The study group of inscriptions is located on the facade of Mount Dedan (Dedan - Al-Khuraybah) in Al-Ula Governorate, in the form of three groups, the first on the northern side facing the Islamic fort, the second next to the family tombs, and the third on the southern side next to the lion tombs. The study includes six inscriptions, including three dated inscriptions, two of which date back to the beginning of the fourth century AH/tenth century AD 311 AH/923 AD, 312 AH/924 AD. The third is from the beginning of the fifth century AH - the eleventh century AD 417 AH / 1026 AD. The study relies on the development of the shape of the letters on the rock facades, which differ in their development from tombstones or manuscripts on papyrus and paper. The importance of these dated inscriptions lies in the fact that they correspond to the period of the Islamic fortress at the site of Deden, which dates back to the Abbasid-Fatimid period.