In some cases it formed a serf class, e.g.
A little serf boy, seeing Prince Andrew, ran into the house.
Nicholas, who, as the roads were in splendid condition, wanted to take them all for a drive in his troyka, proposed to take with them about a dozen of the serf mummers and drive to "Uncle's."
The serf, who was also a soldier, revolted against bondage.
The thrall had a house of his own and was rather villein or serf than slave, having rights and a legal price by law.