But the Picts all but “mysteriously” disappeared, leaving a rich inheritance of carved stones, place names and settlements across Scotland - but with little written clue as to what happened to them.
While the first mention of the Picts was made by a Roman chronicler in 287, no written record of them exists from around 900 onwards.
What is known is that Irish Scot Kenneth MacAlpin made claims to the kingdoms of the Picts, and the Gaels, some point between 839 and 848 - a move which ultimately unified the tribes under the Kingdom of Alba.
The Picts, also documented by Roman chroniclers as the ‘painted people’, disappeared within 50 or 60 years amid a period of potent power play and warfare.
“What is undoubtedly mysterious is the extraordinary disappearance of the culture of the Pictish people within the course of the first two or three generations of mac Alpin kings,” noted Michael Lynch in his book Scotland: a New History.
Kenneth I’s rule over the Picts came after the brutal 839 Viking attack on the Pictish kingdom of Fortriu, centred on modern-day Moray, which left the king Eóganan mac Óengusa, his brother Bran and the King of Dalriada dead. A power vacuum was left, which Kenneth swiftly moved to fill.
One of the more flamboyant accounts of Kenneth’s manoeuvring - known as the Treachery of Scone - has become the stuff of legend.
Indeed the story was so vivid, it was included in a list of “learned tales” in the 11th Century which were judged suitable for reciting at a feast.
Benjamin Hudson, in his book The Picts, said: “How Kenneth achieved his triumph is the subject of a legend that circulated for centuries among the Irish concerning a fatal banquet that he gave for the Pictish nobles at Scone.
He adds: “The story claims that the Picts were invited to a feast where the benches had been loosened so that a peg could be drawn from them and the seat would collapse.
“The Pictish nobles were in the midst of eating when the Scots withdrew the peg, and in the ensuing confusion, killed them.”
While the story undoubtedly intrigues, its factual value is less than certain.
What is known is that the new King first established himself at Fortriu and used it as his main power centre as he extended his lordship eastwards, taking a fortress at Forteviot and then building his dynasty at Scone.
Kenneth I died in 858 with the kingship passing to his brother Domnall and then his son, Constantine I.
Constantine has historically been listed as King of Picts in some accounts of the day but also as King of Scots in more modern references, which perhaps illustrates the shifting shape of Scotland of the day.
What is known is that Picts and Gaels were united in their attack on Viking invaders coming from Ireland, Northumbria and northern Britain.
A “great slaughter of the Picts” at Dollar was recorded in 875 with Constantine captured two years later.
Some say he was beheaded on a Fife beach following a battle at Fife Ness near Crail.
The title King of the Picts died with Constantine I, recorded as the 70th and last king.
His son was known as King of Alba with the Picts - so dominant for centuriees - swallowed up by the new Kingdom which was increasingly influenced by Christianity.
Elizabeth Sutherland, in her book In Search of the Picts, noted: “The Picts were forced to submit to a growing intolerance of their laws and customs both secular and ecclesiastical. The re-founded church centres were no longer Pictish in their outlook, but altogether Scottish.
Sutherland added: “Reading between the lines, the proud Picts were deeply resentful of any attempt to make them conform to new ideas.
“This must have been the time when old annals, records and gospel manuscripts kept in the old Pictish monastic sites were thrown away, burned or hidden.”
By 900, Constantine II, the Christian grandson of Kenneth, with the Bishop of St Andrews, declared that the laws and disciplines of the faith, the churches and the gospels “should be kept in conformity with the Scots.”
And from there, no contemporaneous mention of the Picts appears.
But what remains is a vivid legacy of art, craft and sculpture - a testament to the Dark Age warrior who ruled Scotland for so long - that still stands strong today.