What type of language was spoken by the Picts, and even how many languages were in use, has been a source of controversy and disagreement for many years.

There are three sources for the language of the Picts, contemporary and later documents, place-names, and folk traditions and legends. All three are extremely sparse.

The contemporary documents are inscriptions on stone slabs using the Ogham alphabet. These can be read letter by letter but the resulting texts are incomprehensible. No satisfactory explanation of this has yet been proposed.

Manuscripts date from the twelfth century but may contain material as early as the ninth century. Among these is the List of Kings, which gives information that can be cross-checked from about 550 CE onward. Before this the list cannot be relied upon. The names of the kings are of primary interest for the question of language. They fall into two groups, those that are clearly P Celtic and those that cannot be classified.

Reliable Latin authors list the tribes in Scotland and the names of many places and natural features. All these names, with the exception of some of the names of natural features, are P Celtic.
Place-name evidence also supports the P Celtic hypotheses.

In addition to the names containing Pitt, other generic elements (tref, penn, cair etc.) mark the use of a P Celtic language not only in the Pict land but also over all of southern Scotland and large areas of the north. This language would seem to be close to, but not identical with, Britonnic. It has been labelled Cumbric. An affinity with Gaulish has been suggested based upon very weak evidence.

There is, as yet, no place-name evidence that would support another language being used in the area prior to the use of Cumbric.

Scotland, like most of the rest of Europe, has preserved natural feature names which do indicate the presence of a non-Celtic language. In the case of Scotland, where there is no record of the presence of languages other than Indo-European, this can be explained by postulating the presence of Indo-European speakers before Celtic came to be used in the region.

Finally there is a group of names of natural features and habitation sites that as yet, defy all classification.
the name Pict
the divisions of the Picts