Bronze Age
Bronze Age refers to a stage of development during which a society learns to cast bronze by smelting tin and copper and to use the alloy predominantly in tools, weapons, jewelry and cookware. It was preceded by the Stone Age. 

In the 24th century, the Mintakan civilization on Mintaka III was undergoing its Bronze Age, as they had not yet developed the techniques to forge iron. ()

The Takarians of  were undergoing their Bronze Age when Dr. Arridor and  settled on their planet. They were considered to be a pre-industrial civilization. ()

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de:Bronzezeit
Historical eras