I think not. He was describing a theoretical state pre-existing all civil society. Also the term 'Dark Ages' is a bit of a canard, at least in its later stages following the Germanic tribes settling into their new digs. Of course the manorial system of serfdom was tough, but not generally brutal, and originated in late antiquity and continued, in the West, well into modern times.
Yes, serfdom existed in much of Russia in the late 19th century and in some parts of Russia later than that. You are correct, the manorial system was not brutal. The brutality part is associated with the development of the social structure, especially when one lord would force vassalage over another. This was perhaps a 200 year interval.