When did the druids live?

Druids were a prominent part of ancient Celtic society, primarily during the Iron Age, which spanned from around 800 BCE to the Roman conquest of Britain in the 1st century CE. They were most active from approximately 300 BCE to 100 CE, serving as priests, educators, and legal authorities. The druids were particularly associated with the Celtic tribes in regions that are now Britain, Ireland, and parts of continental Europe. Their practices and influence began to decline with the spread of Christianity and the Roman Empire.