The discovery that combining copper with a little tin will give you bronze is the most important event. This discovery led the peoples of Europe and Asia down their 4,000-year path toward conquest and world dominance that shaped the world today. The later discovery of iron and subsequent discovery that combining iron with carbon gives you steel, were equally-important events. Steel technilogically separated the people of Europe and Asia from the people of Africa, Australia, and the Americas. But the path all began with the invention of bronze.