>>515137140
according to Christiansen large parts of Denmark, especially coastline, were depopulated due to raids of Slavic pirates.

Pagan West Slavic realms were warlike nations during that time (10th - 12th centuries). As Eric Christiansen describes:

Page 59:

"(...) Slavic societies were heavily militarized; that military organization developed during the 9th and the 10th centuries, as the result of living constantly between the Viking hammer and the Emperor's anvil, not even mentioning Danish kings and German bishops. (...)"

And as Christiansen points out, since that time the shoe was on the other foot because now Slavic Vikings (pirates) were raiding Denmark.