Caviar sturgeon from the Sea of Azov began reaching the tables of aristocratic and noble Byzantine Greeks in the 10th century, after the commencement of large-scale trading between the Byzantine Empire and Kievan Rus'. The main types of caviar are Beluga, Sterlet, Kaluga hybrid, American osetra, Ossetra, Siberian sturgeon and Sevruga. The rarest and costliest is from beluga sturgeon that swim in the Caspian Sea, which is bordered by Iran, Kazakhstan, Russia, Turkmenistan, and Azerbaijan. Wild caviar production was suspended in Russia between 2008 and 2011 to allow wild stocks to replenish. Azerbaijan and Iran also allow the fishing of sturgeon
The Types of the Scandinavian Medieval Ballad differences of the variants of the ballad and how they differ, and comprises a list of appearances in various Nordic ballad collections. Almost all of the ballad types given in the Danish (DgF), Faroese (CCF), Icelandic (IFkv), or Swedish (SMB) ballad type listings also have a specific TSB type listing. (The exceptions are a few texts, which now are known to be of rather recent origin, or are otherwise found to be deficient.) Norsk visearkiv, which is responsible for the corresponding Norwegian ballad project, has decided to employ the TSB classification directly. Many Scandinavian ballad types are also easily recognised