The Frisian Kingdom, also known as Magna Frisia, is a modern name for the post-Roman Frisian realm in Western Europe in the period when it was at its largest (650–734). This dominion was ruled by kings and emerged in the mid-7th century and probably ended with the Battle of the Boarn in 734 when the Frisians were defeated by the Frankish Empire. It lay mainly in what is now the Netherlands and – according to some 19th century authors – extended from the Zwin near Bruges in Belgium to the Weser in Germany. The center of power was the city of Utrecht.

The Frisii were an ancient tribe, living in the low-lying region between the Rhine–Meuse–Scheldt delta and the River Ems, sharing some cultural and linguistic elements with the neighbouring Celts. The newly formed marshlands were largely uninhabitated until the 6th or 5th centuries BC, when inland settlers started to colonize the area. As sea levels rose and flooding risks increased, the inhabitants learned to build their houses on village mounds or terps. The way of life and material culture of the Frisii hardly distinguished itself from the customs of the Chaucian tribes living farther east. The latter, however, were considered to be part of the Germanic tribal confederation.