Friso-Saxon is a collective name for a certain group of dialects belonging to the West Germanic languages

West Germanic languages

The West Germanic languages constitute the largest of the three traditional branches of the Germanic family of languages and include languages such as German, English, Dutch, Afrikaans, the Frisian languages, and Yiddish...

. Although they are a variant of the Low Saxon language as a whole, these dialects have undergone strong influences from the Frisian language. Most of the Friso-Saxon dialects were Frisian dialects themselves in the past, until Frisian was replaced with Low Saxon in the Late Middle Ages

Late Middle Ages

The Late Middle Ages was the period of European history generally comprising the 14th to the 16th century . The Late Middle Ages followed the High Middle Ages and preceded the onset of the early modern era ....

. However, Frisian has remained a substratum

Substratum

In linguistics, a stratum or strate is a language that influences, or is influenced by another through contact. A substratum is a language which has lower power or prestige than another, while a superstratum is the language that has higher power or prestige. Both substratum and superstratum...

 since then in the regions concerned. The only exception to this rule is Stellingwarfs

Stellingwarfs

Stellingwarfs is the form of Dutch Low Saxon spoken in Ooststellingwerf and Weststellingwerf in the Dutch province of Friesland.By some observers included within Stellingwarfs is Veenkoloniaals, which is spoken in the village of Noordwolde in the Dutch province of Friesland.Stellingwarfs is easily...

, a Low Saxon dialect which has undergone influence especially from West Frisian

West Frisian language

West Frisian is a language spoken mostly in the province of Friesland in the north of the Netherlands. West Frisian is the name by which this language is usually known outside the Netherlands, to distinguish it from the closely related Frisian languages of Saterland Frisian and North Frisian,...

. Most of the other Friso-Saxon dialects underwent most influence from East Frisian Low Saxon

East Frisian Low Saxon

East Frisian Low Saxon is a West Low German dialect spoken in the East Frisian peninsula of northwestern Lower Saxony. It is used quite frequently in everyday speech there. About half of the East Frisian population in the coastal region uses Platdüütsk. A number of individuals, despite not being...

, except for the dialect of Dithmarschen

Dithmarschen

Dithmarschen is a district in Schleswig-Holstein, Germany. It is bounded by the districts of Nordfriesland, Schleswig-Flensburg, Rendsburg-Eckernförde, and Steinburg, by the state of Lower Saxony , and by the North Sea.-Geography:The district is located on the North Sea...

 which underwent most influence from North Frisian

North Frisian language

North Frisian is a minority language of Germany, spoken by about 10,000 people in North Frisia. The language is part of the larger group of the West Germanic Frisian languages.-Classification:...

.