The ancient inhabitants of present-day Bulgaria had knowledge of metals and metalworking from the end of the Chalcolithic Age, when they extracted and processed copper and gold.

In the fourth millennium BCE, people invented bronze, an alloy of copper and tin. Objects made from this alloy could be remelted after wearing out or breaking and then recast.

Metals extracted from ores were processed by master craftsmen—founders and smiths—who used stone and clay molds to cast tools, instruments, weapons, ornaments, jewelry, and other items. Once cast, the objects were further processed by forging, filing, and polishing, and then decorated. One surviving hoard of stone molds from Pobit Kamak in the Varna region reveals the variety of objects produced in a single bronze foundry during the Late Bronze Age: tools (chisels, axes, awls, knives), weapons (swords), scepters, ornaments (appliqués, pendants, jewelry), and even the inner bronze lining of discs (lids) like those from Valchitran. Many similar finds from ancient workshops at the end of the Bronze Age have been discovered in present-day Bulgaria.

Numerous bronze finds that have survived to our day reveal the tools and instruments the Thracians used during the Bronze Age and Early Iron Age. During the Late Bronze Age, a tradition emerged of burying "treasures" in the ground—collections of hundreds of bronze objects, including cutting tools (primarily sickles and hollow axe heads called "celts"), chisels, and occasionally weapons. The reason for this practice remains unclear, though it may relate to the value of the metal or the use of these objects as a medium of exchange.