1.The Celtics Celt,[kelt] The Celts were tribes invaded from Europe after about 800 BC. developed knowledge of how to make stronger weapons and tools using iron:the start of the Iron Age. 1. The Celtics ❖ Celt, [kɛlt] ❖ The Celts were tribes invaded from Europe after about 800 BC. ❖ developed knowledge of how to make stronger weapons and tools using iron: the start of the Iron Age