The former Frisian kingdom (Magna Frisia) had been incorporated into Francia after the Frisian–Frankish wars, that ended with the victory of the Frankish troops led by majordomo Charles Martel at the Battle of the Boarn in 734.

In turn the Frankish emperor Louis the Pious and his successor Lothair I, ruler of Middle Francia since 843, tried to pacify the Viking leaders such as Harald Klak or Rorik of Dorestad by vesting them with large estates in the Frisian lands.

In 873 the Viking leader Rodulf Haraldsson was killed by the inhabitants of Eastergoa and from 879 Harald Klak's son Godfrid plundered the coast down to Flanders until he finally came to terms with Emperor Charles the Fat upon the 882 Siege of Asselt and was appointed a "Duke of Frisia".

He was killed in 885 by the emperor's vassal Henry of Franconia, aided by the local count Gerolf, who in turn was vested with large estates on the southern Frisian coast, that later emerged as the County of Holland.

In 925 the Frisian lands together with Lotharingia were finally incorporated into East Francia by King Henry the Fowler and became a part of the Holy Roman Empire from 962 onwards.

About 1300 the "Seven Frisian Seelands" stretched along the coast from Westergo on the Zuiderzee to the border with Land Hadeln on the right shore of the Weser mouth, then a possession of the Ascanian dukes of Saxe-Lauenburg.

In 1464 the Habsburg emperor Frederick III elevated the mighty chief Ulrich and his descendants of the Cirksena dynasty to heritable Counts of East Frisia, an Imperial State they held until 1744.

Finally in 1498, Frederick's son King Maximilian I ended the freedom in the remaining Frisian lands, when he appointed the Wettin duke Albert III of Saxony his stadtholder in Frisia for a loan of 300,000 guilders.

Frisia was largely controlled by local rebels, supported by troops of Duke Charles II of Guelders, who had been at war with Burgundy and Saxony for several years.