Since 2006, an international team of researchers at the UCL Institute of Archaeology have been using analytical chemistry techniques to uncover more details about the production techniques employed in the creation of the Terracotta Army. Using X-ray fluorescence spectrometry of 40,000 bronze arrowheads bundled in groups of 100, the researchers reported that the arrowheads within a single bundle formed a relatively tight cluster that was different from other bundles. In addition, the presence or absence of metal impurities was consistent within bundles. Based on the arrows’ chemical compositions, the researchers concluded that a cellular manufacturing system similar to the one used in a modern Toyota factory, as opposed to a continuous assembly line in the early days of the automobile industry, was employed.