Tell al-'Ubaid is the name of an archaeological site in southern Iraq where a distinctive type of painted pottery dating to the fifth millennium BC was found. When the names for the different periods in Mesopotamian archaeology were agreed upon at a meeting of archaeologists in 1929, 'Ubaid became the name for the period c. 4500-4000 BC It has since been extended to cover all of the fifth millennium in southern Mesopotamia. Pottery of typical 'Ubaid type - highly fired, almost greenish-yellow, with black, geometric decoration - has been found at several sites on the coast of the UAE, including al-Madar, the shell mounds of Hamriyah in Sharjah, and Jazirat al-Hamra in Ras al-Khaimah. Was it being traded by Mesopotamian fishermen or merchants who came south looking for luxuries, such as pearls (pearling)? Was it acquired by ancient inhabitants of the Emirates - perhaps fishermen - who sailed north and visited southern Iraq? Scholars are uncertain of the means whereby it arrived in the Emirates.