In 2009, a boat - shaped cup was excavated from the Xujiaha site at Pengshui in Chongqing city. Scanning electron microscopy and energy - dispersive spectrometry analysis showed that the surface of the boat – shaped cup contained a large amount of Cu and Pb and a trace amount of Sn. Additionally, a small copper block isolated from the boat - shaped cup was found to be made of Cu, Sn and Pb. X - ray diffraction analysis of a blue-gray material in the cup showed that it was comprised of cassiterite (Sn02), copper oxide (CuO) and carbon (C). These results indicated that the Ba People, who lived during the Shang and Zhou dynasties, knew the properties of bronze alloys and had grasped the technology of bronze smelting and casting. This finding suggests that boat-shaped cup was used as a crucible in the bronze smelting and casting.