Wikipedia ("Reich"):
The [Proto-Indo-European] root "*reg-" (rule) is non-existent in Slavonic. There is also no native Slavic root for "king" and "kingdom" or similar words, probably because the early Slavic societies were highly democratic and ruled by an ancient form of parliament "wiec". Hence, Slavonic words generally meaning "king" derive from the name of Charlemagne in Old French, "Karol". Similarly, the words that mean more or less the aristocratic title "prince" come from Gothic "kunings" (with many local phonetic changes, e.g. "knędz" in Old Polish, "książę" in Polish and "kniaz'" in Ruthenian).
The title царь (tsar), of course, like kaiser (and the Arabic and Persian qaysar), derives from the name Caesar.
There are, however:
господь (gospod', "lord"), государь (gosudar', "sovereign"), воевод (voyevod, literally "war-leader"), вождь (vozhd', "leader"), and хозяин (khozyain, "lord"), all of which I believe to be native Slavic words.
When Romania belonged to the Ottoman Empire, it was divided into two principalities, Moldavia and Wallachia, whose rulers bore the title of Hospodar (= государь), even though the Romanians speak a Romance not a Slavic language (and the hospodars themselves were always Phanariote Greeks).
The [Proto-Indo-European] root "*reg-" (rule) is non-existent in Slavonic. There is also no native Slavic root for "king" and "kingdom" or similar words, probably because the early Slavic societies were highly democratic and ruled by an ancient form of parliament "wiec". Hence, Slavonic words generally meaning "king" derive from the name of Charlemagne in Old French, "Karol". Similarly, the words that mean more or less the aristocratic title "prince" come from Gothic "kunings" (with many local phonetic changes, e.g. "knędz" in Old Polish, "książę" in Polish and "kniaz'" in Ruthenian).
The title царь (tsar), of course, like kaiser (and the Arabic and Persian qaysar), derives from the name Caesar.
There are, however:
господь (gospod', "lord"), государь (gosudar', "sovereign"), воевод (voyevod, literally "war-leader"), вождь (vozhd', "leader"), and хозяин (khozyain, "lord"), all of which I believe to be native Slavic words.
When Romania belonged to the Ottoman Empire, it was divided into two principalities, Moldavia and Wallachia, whose rulers bore the title of Hospodar (= государь), even though the Romanians speak a Romance not a Slavic language (and the hospodars themselves were always Phanariote Greeks).