Tin bronze replaced arsenical copper as the preferred alloy in the Levant for reasons that have long been debated. Found almost exclusively in graves, these two types of copper alloys share nearly identical mechanical properties. The Bronze Age cemetery of ‘Enot Shuni has yielded the first metals ever analysed from an uninterrupted stratigraphic sequence in the Levant, spanning the earliest adoption of tin bronze from the Early Bronze Age (EB) IV through the Middle Bronze Age (MB) II (c. 2300–1530 bc). SEM–EDS analysis of these artefacts, combined with a compositional meta-database of all previously published EB IV – MB II alloys, reveals diachronic alloy progression as selected by populations of the Levant. It has long been qualitatively understood that bronze became the primary alloy by the MB II. These results verify this trend and quantify human demand, showing that tin importation increased by 103% and arsenic content decreased by 49% throughout these periods. This shift in technological choice is attributed to cultural reorientation from the Egyptian to Mesopotamian sphere of influence, as well as to tin's appreciable fuel efficiency over pure copper and arsenical copper in light of unprecedented timber shortages.