What happened durning the early copper age?

The Copper Age, also called the Eneolithic or the Chalcolithic Age, has been traditionally understood as a transitional period between the Neolithic and the Bronze Age, in which a gradual introduction of the metal (native copper) took place, while stone was still the main resource utilized. Recent archaeology has found that the metal was not introduced so gradually and that this entailed significant social changes, such as hierarchical leadership, developments in the type of habitation (larger villages, launching of fortifications), long-distance trade, and copper metallurgy.

Roughly, the Copper Age could be situated chronologically between the 5th and 6th millennium BC in places like the archaeological sites of Majdanpek, Јarmovac and Pločnik (a copper axe from 5500 BC belonging to the Vinča culture).[1] Somewhat later, in 5th millennium BC, metalwork is attested at Rudna Glava mine in Serbia,[2] and at Ai Bunar mine in Bulgaria.[3]

3rd millennium BC copper metalwork is attested in places like Palmela (Portugal), Cortes de Navarra (Spain), and Stonehenge (United Kingdom). However, as often happens with the prehistoric times, the limits of the age cannot be clearly defined and vary with different sources.