In researching the history of serfdom in Russia, and the privileges of the Boyars that entrenched in a system (now abolished) called mestnichestvo, I found this 1856 source that touches on comparison of serfs and "gypsies" in Bessarabia. Eastern Europe, Middle East, affected by pulls by the Byzantine system and the Germano-Romanic (including Poles, Hungarians and Germans), in how ranks were absorbed, administered, and whose were hereditary. See The Russian Empire, Its People, Institutions and Resources, Volume 2 by August Freiherr von Haxthausen at pp. 152 ff. Wallachian ranks:
Wallachia: All residents were "Tzarani" from a Wallachian word for country, or tzar. Work: as peasants, in fields, laborers, "field-watchmen", herders. Then this part: the only equivalent of serfs, in Russia tied to the land, belonging physically to the landowner, in Bessarabia, were the "gipsies". From early times they belonged to the privileged classes.
Then the source addresses subgroups of the privileged,
This is a kind of bookmark to get back to the human issue of one group driven to own another, and how to get around the customs and repercussions of servitude. The effect: even poor health for those on the lower rungs, see http://blogs.reuters.com/great-debate/2013/10/30/why-low-social-status-can-be-bad-for-your-health/