West-Friesland is a region in the north-western Netherlands, in the province North Holland. The region covers an area of about 800 km² and consists of the municipalities Andijk, Drechterland, Enkhuizen, Hoorn, Medemblik, Noorder-Koggenland, Obdam, Opmeer, Stede Broec, Venhuizen, Wervershoof, Wester-Koggenland and Wognum.

The river Fli (or Flehi), an extension of the IJssel branch of the Rhine, divided the northern part of the Netherlands, which at the time all belonged to Friesland, into a western and eastern part. In the 11th century, after heavy rainfalls, the river flooded and inundated large parts of the land; and not long after the Zuiderzee bay was formed.

West-Friesland has from the 13th century been protected by the Westfriese Omringdijk, a dike that was built to protect the land against the salt water of the Zuiderzee. This dike currently still protects the eastern part of West-Friesland against the IJsselmeer.

For about 300 years, West-Friesland operated as an autonomous area as the West Frisians did not want to be subjected to Hollandic authorities. Floris V, Count of Holland tried hard during his reign, but it was his successor John II who finally defeated the West Frisians in 1297, putting an end to their independence. However, even though West Friesland formed one united province with Holland in the Dutch Republic, it was recognized a separate region and the parliament of said province, commonly known as Holland, was formally known as the States of Holland and West-Friesland, showing that West-Friesland was still recognized in its own right.