This poster presents the results of the excavations of an urban district in ancient Dadan, in the al-ʿUlā valley (north-west Arabia), conducted by the team of the Dadan Archaeological Project (CNRS/RCU/ AFALULA) between 2020 and 2023. The excavation data were processed jointly with the ECOSeed archaeobotanical project. This multidisciplinary approach provides critical new insights into the development of one of the major ancient northwest Arabian oases. The excavations revealed the earliest safely dated domestic architectural remains in the oasis. The results also enable a reassessment of the earlier archaeological evidence, suggesting a first peak in the urban development of the oasis during the Bronze Age. This excavation then revealed a virtually continuous urban occupation through the Iron Age until the early 1st millennium AD, in particular with periods of reorganization of the district between the 8th and 5th centuries BC, and again between the 4th and 2nd centuries BC. Many evolutions in the material culture and lifestyle of the population can also be observed over more than 2,000 years of occupation, such as changes in the diet, agricultural practices, pottery production, and macro-lithic technology.