date of establishment charles mackay says that a people called the frieslanders were holding an annual diet under an oak tree at aurich as early as the th century quote as early as the eleventh century they had formed a general confederacy against the encroachments of the normans and the saxons which was divided into seven seelands holding annually a diet under a large oak tree at aurich near the upstalboom the church exterminated them for witchcraft almost wiping them from the pages of history almost ref