I am reading Tolstoy's War and Peace (which is far more entertaining than I expected). There are several characters who are referred to as Princes: Prince Bolkonsky and Prince Kuragin to name two. And while I realize they are fictional characters, I can't figure out how they would have figured into the scheme of Russian nobility. There was the Tsar who Tolstoy refers to as the Emperor. Would these characters have been related by blood to Tsar Alexander I or were these titles of a different sort?
Here Prince is used to translate the Russian князь knjaz'. Etymologically, the title is a borrowing of Proto-Germanic *kuningaz. It's been around for a while, as the difference between the PGmc and the Modern Russian forms shows clearly. This is to say, there was no necessary relation to the Tsar' carried with the title knjaz'. It was, in fact, occasionally awarded by the Tsar'. On the other hand, relatives of the Tsar' were velikie knjazja 'Grand Princes/Dukes' or velikie knjagini 'Grand Princesses/Duchesses'. These two titles were generally restricted to the Tsar's children and grandchildren.
It is more or less standard nowadays to translate the Russian (and some other slavic/orthodox countries) knyaz (or knjaz as /u/rusoved spells it) with Duke and Velkye Knyaz with Grand Duke.
The Velkye Knyaz title was generally reserved for the Imperial family, while there could be many Knyaz among the nobility.
The title is hard to translate to English, since English nobility does not contain the title. It does exist in German and Russian though. The titles Duke and Count appeared iun the Russian nobility with Peter the Great - both as a Russian title instituted by Peter and with the German Baltic nobility in the from Sweden conquered Baltic provinces of Estonia and Livonia.
The German equilent of the Prince title is Fürst, which is a rank above Hertog (Duke).
There was the Tsar who Tolstoy refers to as the Emperor.
I assume Tolstoy used the Russian word, and the translator has rendered it as "Emperor" which is what it means. Which seems odd to us because we think of the title as "Tsar" not "Emperor" (the same way we do with "Sultan")
Was "Tsar"/"Czar"/"Tzar" formerly not sufficiently recognised in English, such that a translator of the book might feel the need to translate the title, or is the translator just being overly thorough?
As far as I understand it from The History of Russia (Riasanovsky) this all started with appanage Russia, where each city had its own titular prince, and they formed a confederacy ruled over by the 'Grand Prince' who was at Kiev. This is after the Mongol invasion obviously, and things changed after the shift of importance toward Moscow.
Kiev in particular did not follow the 'inheritance' rule; it appears that the city voted for (and reserved the right to expel) their Grand Prince, and even made him sign a contract limiting his power.