The four elements of the Land of Frankincense vividly depict the centuries-long frankincense commerce that thrived in this region. They are a remarkable testament to the civilizations that have existed in southern Arabia since the Neolithic period. The frankincense trees of Wadi Dawkha, as well as the ruins of the caravan oasis of Ubar in Shisr and the affiliated ports of Khor Rori and Al-Baleed, vividly depict the frankincense trade that thrived in this region for many centuries as one of the most important trading activities of the ancient and medieval world. The frankincense tree (Boswellia sacra) can still be found in Wadi Dawkha, and frankincense is still gathered there. The Wadi drains...