Map of britain
Northern England especially was barely under the control of any king. In fact, there was only one castle in all of Anglo-Saxon England…..because castles were meant to not just resist invaders but also to resist uprisings by hostile, enslaved local populations. An island like England did not need castles for lording it over a free people who accepted their rulers
Map of Charlemagne' Empire, circa 800 AD. Charlemagne 2 April 742/747/748 – 28 January 814), also known as Charles the Great or Charles I, was the King of the Franks from 768, the King of Italy from 774, and from 800 the first emperor in western Europe since the collapse of the Western Roman Empire three centuries earlier. The expanded Frankish state he founded is called the Carolingian Empire.