Serfdom in Russia
In tsarist Russia, the term serf (Russian: крепостной крестьянин, romanized: krepostnoy krest'yanin, lit. 'bonded peasant') meant an unfree peasant who, unlike a slave, originally could be sold only together with the land to which they were "attached". However, this had stopped being a requirement by the 19th century, and serfs were by then practically indistinguishable from slaves.