Oasian agrobiodiversity in Northwestern Arabia has a long and deep history which reflects adaptation strategies to arid climatic conditions and intense trade activities. New archaeobotanical investigations from two major ancient cities of the oasis of Al Ula, namely Dadan and Hegra, and other satellite sites offer a unique opportunity to reconstruct the long-term evolution of the plant economy on more than 3500 years, integrating agro-sylvo-pastoral system and medium- and long-distance trade activities. Our communication aims to present the latest results of the plant macro-remains analyses (seeds & fruits, charcoal) encompassing a large dataset of radiocarbon dating providing new insights into the diachronic evolution of oasian agriculture economies from the end of the Bronze age to the Islamic times (~2500 BCE-1200 CE). We’ll discuss the first evidence for crops that are cereals during the second half of the 3rd mill. BCE, then date palm at the end of the 2nd mill. BCE, and the emergence of several additional cultivated plants in the Late Iron age and Antiquity, with a special focus on fruit trees (Vitis vinifera, Olea europaea, Ficus carica) and cotton (Gossypium sp.). The new data from the Medieval period finally reveals the cultivation of a wide diversity of fruit trees - in particular from the Prunoidae and Maloidae tribes - in the oasis, some of them attested for the first time on the Arabian Peninsula. Comparison with the few other botanical data available in Northwestern Arabia for contemporaneous periods (e.g. Tayma and Kilwa) will highlight the common trends and local particularities in order to attempt a first regional overview.