There was considerable regional variation in the types of ceramic vessels produced in Mesopotamia during the Seleucid and Parthian periods. Classical influences are evident in Mesopotamia and the Persian Gulf, although direct evidence for Roman imports is rare. A distinctive feature of Mesopotamian manufacture was the use of blue, green or yellow alkaline glazes. This is a particularly attractive example as the original deep blue colour survives unweathered. The glazes on Parthian pottery form part of a long tradition of alkaline glazing in Mesopotamia. Glazes were made by mixing the ash produced by burning desert plants with crushed quartz pebbles or quartz sand. The blue and green colours are due to the presence of minor amounts of iron oxide, with or without copper. There is no evidence for the use of lead glazes in the Parthian and later Sasanian empires, although they were used both by the Romans in the west and in the east, in China.