Anglo-Frisian

The Anglo-Frisian languages are a proposed sub-branch of the West Germanic languages encompassing the Anglic languages (English, Scots, extinct Fingallian, and extinct Yola) as well as the Frisian languages (North Frisian, East Frisian, and West Frisian). While this relationship had considerable support historically, many modern scholars have criticized it as a valid phylogenetic grouping. Instead, they believe that the Ingvaeonic languages comprised a dialect continuum which stretched along the North Sea, finally diverging into distinct languages – Old English, Pre–Old Frisian, and Old Saxon – during the Migration Period in the 5th century. There are still proponents of an Anglo-Frisian node in the West Germanic tree, citing strong archeological and genetic evidence for the comingling of these groups. In the 1950s, Hans Kuhn argued that the two languages diverged at the Ingvaeonic level, but later "converged". He argued that this convergence explained the striking similarity of the two languages while also explaining the issues in chronology. This view has been dismissed as improbable given the geographic divide.

The Anglo-Frisian languages have been distinguished from other West Germanic languages due to several sound changes: besides the Ingvaeonic nasal spirant law, which is present in Low German as well, Anglo-Frisian brightening and palatalization of /k/ are for the most part unique to the modern Anglo-Frisian languages: