The Picts were a group of peoples who lived in what is now northern and eastern Scotland (north of the Firth of Forth) during Late Antiquity and the Early Middle Ages. Where they lived and what their culture was like can be inferred from early medieval texts and Pictish stones. Their Latin name, , appears in written records from the 3rd to the 10th century. Early medieval sources report the existence of a distinct Pictish language, which today is believed to have been an Insular Celtic language, closely related to the Brittonic spoken by the Britons who lived to the south. Picts are assumed to have been the descendants of the Caledonii and other Iron Age tribes that were mentioned by Roman historians or on the world map of Ptolemy. The Pictish kingdom, often called Pictland in modern sources, achieved a large degree of political unity in the late 7th and early 8th centuries through the expanding kingdom of Fortriu, the Iron Age Verturiones. By the year 900, the resulting Pictish over-kingdom had merged with the Gaelic kingdom of Dál Riata to form the Kingdom of Alba (Scotland); and by the 13th century Alba had expanded to include the Brittonic kingdom of Strathclyde, Northumbrian Lothian, as well as Galloway and the Western Isles. Pictish society was typical of many Iron Age societies in northern Europe and had parallels with neighbouring groups. Archaeology gives some impression of the society of the Picts. While very little in the way of Pictish writing has survived, Pictish history since the late 6th century is known from a variety of sources, including Bede's Historia ecclesiastica gentis Anglorum, saints' lives such as that of Columba by Adomnán, and various Irish annals. Definitions and etymology There has been substantial critical reappraisal of the concept of "Pictishness" over the past few decades. The popular view of the Picts at the beginning of the twentieth century was that they were exotic "lost people". It was noted in the highly influential work of 1955, The Problem of the Picts, that the subject matter was difficult, with the archaeological and historical record frequently being at odds with the conventional essentialist expectations about historical peoples. Since then, the culture-historical paradigm of archaeology that had been dominant since the late nineteenth century gave way to the processual archaeology theory, formerly known as the New Archaeology. The difficulties with Pictish archaeology were due to