File:Urfa museum Uruk period wall mosaic technique - Chalcolithic 4956.jpg

English: The 4th millennium BC saw clay nails that were fired to be used in temples and other monumental structures representing the magnificence of the Uruk culture, used as mosaic like wall decorations in the following periods. The clay nails, that had conical shaped sharp tips, were inserted into wet and thick clay surfaces to create mosaics that would later be painted over in black, red and white colours. This method, which was first used in the decoration of the walls of monumental structures in South Mesopotamia, was also similarly used at the trade colonies of the Middle Euphrates region. The decorations would consist of diamond, triangle, straight, and serpentine shapes. The embellishments on bull shaped clay tablets on the walls were made using the same method. The Uruk Period is ranked with the Bronze Age, but I think the display was in the chalcolithic hall. At least nr. 14 in one picture is indicated as being from then.