Optically stimulated luminescence dating of the city wall system of ancient Tayma (NW Saudi Arabia)

In addition to a series of chronological markers (artefacts, pottery) in the archaeological contexts of ancient Tayma (NW Saudi Arabia), optically stimulated luminescence (OSL) and radiocarbon dating techniques were applied to generate reliable ages for the city wall system of the oasis. A massive aeolian sand deposit burying the oldest part of the outer wall of Tayma was sampled to obtain a minimum age for the construction of this wall. The sequence of OSL ages from the inactive dune (ID) (4900 ± 300 a, 5100 ± 400 a, 4400 ± 300 a, 3900 ± 200 a, 4000 ± 200 a) is in full accordance with 14C-AMS ages of charcoal embedded into the same dune (4190–4420 cal BP, 3870–4080 cal BP). Underlying alluvial samples from the inactive gravel sheet (IGS) in contrast give maximum ages for the construction which scatter between 6600 ± 300 a and 4900 ± 400 a. The new dating sequence provides evidence that the oldest part of the ancient city wall system already existed in the 2nd half of the 3rd mill. BC which is earlier than expected thus far from archaeological and architectural interpretation.

► This is the first attempt combining OSL dating and archaeological research in NW Saudi Arabia.
► Aeolian and alluvial deposits are associated with the existence of the ancient city wall.
► Dating their phase of accumulation provides minimum and maximum ages for the construction.
► OSL and 14C ages suggest the construction of the city wall during the 2nd half of the 3rd mill. BC.