The Druids were preservers and enforcers of tradition among these tribes, passing on an oral literature that did not survive the arrival of Rome and the decline of the Celtic languages and cultures.
They were probably the most learned class among their people and may have passed on to the laity a good deal of practical knowledge in addition to the religious teachings of their polytheistic faith.
Our written sources about the Druids are exclusively Roman. Gaius Julius Caesar’s Gallic Wars ascribed to the Druids among the Gauls the authority to make judgments in disputes both civil and criminal and the use of exile as punishment. Other writers wrote of Druids telling fortunes, receiving instruction in secret, and overseeing sacrifices, including human sacrifices.
They were almost certainly the keepers and designers of the calendar the Celtic tribes followed. Though they have long been associated with Stonehenge in the popular imagination, Stonehenge predates the Druids considerably, and they could not have had anything to do with its construction.
It is primarily the result of historical fads in the 18th and 19th centuries that so many misconceptions about the Druids are lodged in popular thought, many of them the product of poor scholarship or outright fabrication. It is from that period that many “modern druidic movements” stem, some of them claiming an unbroken connection to the Druids of the Iron Age.
Little, too, is known about the Picts, who inhabited Pictland (northern Scotland) from antiquity until the Middle Ages. A loosely affiliated, ethnically similar group of tribes, they confederated into a number of kingdoms (sometimes ruled over by a high king to whom others owed fealty) sometime after the arrival of Romans in the British Isles.
Presumably, the Pictish religion, and perhaps its language, greatly resembled that of other Celtic groups before this time and converted in the fifth and sixth centuries.
Once Christianity was entrenched, the cult of saints was especially prominent in Pictland, with patron saints associated not just with towns and kings as in much of Christendom but with noble families. Kingship generally passed from brother to brother before passing on to a son, favoring experienced leaders over a direct line of succession.
The Picts are famous for their use of war paint and tattoos, and their name derives from the Latin word pingere, for “paint.” This may have been a myth, and it is unlikely they used woad (which takes poorly to skin) to dye themselves blue, as was once thought. The myth may have grown because of the fierceness of the pirates and raiders among the early Picts; such warriors tend to accumulate hearsay around them.