They were the determined opponents of Hildebrand, warm adherents of the Hohenstaufers-Ghibelline rather than Guelph.

Heresy was a plant of early growth in the Netherlands.

As early as the beginning of the 12th century, the notorious Tanchelyn preached at Antwerp, attacking the authority of the pope and of all other ecclesiastics; scoffing at the ceremonies and sacraments of the Church.

Unless his character and career have been grossly misrepresented, he was the most infamous of the many impostors who have so often disgraced the cause of religious reformation.
By more than four centuries, he anticipated the licentiousness and greediness manifested by a series of false prophets, and was the first to turn both the stupidity of a populace and the viciousness of a priesthood to his own advancement; an ambition which afterwards reached its most signal expression in the celebrated John of Leyden.
The impudence of Tanchelyn and the superstition of his followers seem alike incredible.

All Antwerp was his harem.