Modern scholars believe that there were seven ancient Pictish Kingdoms and that their names were
However there is good archaeological evidence and some written evidence that Orkney was also a Pictish kingdom.
From the 6th century AD onwards the Picts came under increasing pressure from the invasions of the Dalriadan Scots in the west and the Vikings in the east. They defeated Dalriada militarily but intermarried repeatedly with the royal house of Dalriada until in 843 AD, Kenneth Mac Alpin took the throne of a united kingdom of Scotland. Gaelic culture and Scots Gaelic gradually supplanted Pictish culture and the Pictish language.
It remains uncertain whether or not the Picts were Celts although most available placename evidence tends to support the theory that they were Brythonic Celts.
You can often tell where Pictish settlement has taken place in the past (in Scotland) from place names. Those prefixed with "Aber-", "Lhan-", "Pit-" or "Fin-" indicate the region was inhabited by Picts in the past (eg: Aberdeen, Lhanbryde, Pitmedden, Pittodrie, Findochty, etc)
See also: Kings of the Picts