Bronze
Bronze here means an alloy consisting primarily of copper, commonly with about 12% tin and often with the addition of other metals (such as aluminium, manganese, nickel or zinc) and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon. These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as stiffness, ductility or machinability.
The archeological period where bronze was the hardest metal in widespread use is known as the Bronze Age. In the ancient Near East this began with the rise of Sumer in the 4th millennium BC, with India and China starting to use bronze around the same time.