South Arabia’s prehistoric monument landscape shows social resilience to climate change

PLOS One | https://doi.org/10.1371/journal.pone.0323544 May 28, 2025 4 / 24 and areas. We conducted a narrowed search within areas we knew to contain monuments as well as areas unknown to us. We adapted survey methods from prior research in a comparable terrain [16,57,58]. In 1996, McCorriston conducted a reconnaissance to Dhofar. Subsequently the team purchased high (0.6m) spatial resolution QuickBird satellite imagery for comprehensive survey. We selected imagery to cover a “T” with 11 of 14 images across the Nejd desert inland of the cloud-forested coastal mountains [59] p.146, Fig 1]. This selection targeted the region known to contain tombs and triliths and is comparable to terrain with these and other early monuments in other areas of Southern Arabia. A few images in the mountains and coastal plain ensured we would also sample there; we chose so that our broader results could be com- pared to others’ [60]. In purchase of specific image blocks for comprehensive coverage—some with monuments, some unknown--we used prior knowledge and Google Earth to select locales accessible by roads and vehicle tracks. Where possible, the team followed established vehicular-tracks both for logistics and to limit our footprint in a fragile ecosystem. Modern routes in the arid and deeply dissected terrain of Southern Arabia typically follow ancient tracks con- strained by drainages and passes. We documented traces leading through areas frequented and shaped by pastoralists

Fig 2. Timeline of major monument types based on multiple radiocarbon determinations from excavated monuments in Hadramawt, Yemen and in Dhofar, Oman. Top register compiles precipitation proxy record from Qunf Cave, Dhofar [51] with Holocene Humid Period proxy records (silt ter- races) in Hadramawt [38]. For Dhofar, platforms (n = 26, 14C = 4,) are black, HCTs (n = 135, 14C = 10) are fuschia, triliths (n = 165, 14C = 2) are blue, and boat graves (n = 22, 14C = 2) are represented in dark purple, with other (infrequent) monument types (yellow, green, pink). Taq denotes “terminus ante quem,” which indicates a stratigraphic position of sample that constrains the dated event to an earlier time; tpq denotes “terminus post quem,” or an event dated after the radiocarbon determination. These priors define eras of monument construction and use. For example, Dhofar platforms appear after 7500 cal yr. BP. Samples here are only from Dhofar [14,52]; radiocarbon calibrations generally match the Bayesian posteriors (horizontal lines) established with comparable data from Hadramawt, Yemen [12,16,38] and observations within the broader literature of Arabian prehistory. (See Supporting S1-Table, S2 Table, S3 Table for details). The long dotted line for HCT reflects stratigraphic evidence of re-use centuries and millennia after primary interments. Image by Shane Scaggs and Joy McCorriston. https://doi.org/10.1371/journal.pone.0323544.g002