When did the picts invade Britain?

The Picts, a group of Celtic tribes from what is now Scotland, did not invade Britain in a single event but were rather present in the region from around the 3rd century AD. They often raided Roman Britain, particularly during the 4th and 5th centuries, as Roman control weakened. Their interactions with the Romans and later Anglo-Saxon settlers were complex and included both conflict and trade. The Picts remained a significant force in the region until their eventual integration into the Kingdom of Scotland in the early medieval period.