In the early Middle Ages, the whole area between the Zwin and Weser rivers was called Frisia/Friesland. The current province of Friesland in the Netherlands is in the middle of that region, but the former area of Frisia was much larger.
To this day, part of the province of Noord-Holland is known as “West-Friesland” [West Frisia] and part of northern Germany is known as “Ostfriesland” [East Frisia]. So West-Friesland is in the province of Noord-Holland, not in the province of Friesland.
Frisia around the year 700. Credits: Richard Prins, Wikimedia (CC-BY-SA)
About Yvette Hoitink
