In the early Middle Ages the Frisian lands stretched from the area around Bruges, in what is now Belgium, to the river Weser, in northern Germany.

This similarity was reinforced in the late Middle Ages by the Ingvaeonic sound shift, which affected Frisian and English, but the other West Germanic varieties hardly at all.

Until the 16th century, West Frisian was widely spoken and written, but from 1500 onwards it became an almost exclusively oral language, mainly used in rural areas.

This practice was continued under the Habsburg rulers of the Netherlands (Charles V, Holy Roman Emperor, and his son Philip II, King of Spain).

This coincided with the introduction of the so-called newer breaking system, a prominent grammatical feature in almost all West Frisian dialects, with the notable exception of Súdwesthoeksk.

[citation needed] A Frisian diaspora exists abroad; Friesland sent more emigrants than any other Dutch province between the Second World War and the 1970s.

In 2010, some sixty public transportation ticket machines in Friesland and Groningen added a West Frisian-language option.

In the same year, West Frisian became an official school subject, having been introduced to primary education as an optional extra in 1937.

So far 4 out of 18 municipalities (Dantumadiel, De Fryske Marren, Noardeast-Fryslân, Súdwest-Fryslân) have changed their official geographical names from Dutch to West Frisian.

One rhyme that is sometimes used to demonstrate the palpable similarity between Frisian and English is "Bread, butter and green cheese is good English and good Fries", which does not sound very different from "Brea, bûter en griene tsiis is goed Ingelsk en goed Frysk".

The varieties on the islands are rather divergent, and Glottolog distinguishes four languages:[16] The dialects within mainstream mainland West Frisian are all readily intelligible.

The Noardhoeksk ("Northern") dialect, spoken in the north eastern corner of the province, does not differ much from Wood Frisian.

While in the Clay Frisian-speaking area ditches are used to separate the pastures, in the eastern part of the province, where the soil is sandy, and water sinks away much faster, rows of trees are used to that purpose.

Although Klaaifrysk and Wâldfrysk are mutually very easily intelligible, there are, at least to native West Frisian speakers, a few very conspicuous differences.

[17] Of the two, Wâldfrysk probably has more speakers, but because the western clay area was originally the more prosperous part of the mostly agricultural province, Klaaifrysk has had the larger influence on the West Frisian standardised language.

There are few if any differences in morphology or syntax among the West Frisian dialects, all of which are easily mutually intelligible, but there are slight variances in lexicon.