Slavs
Standardised Slavic languages that have official status in at least one country are: Belarusian, Bosnian, Bulgarian, Croatian, Czech, Macedonian, Montenegrin, Polish, Russian, Serbian, Slovak, Slovene, and Ukrainian.
History of the Slavic languages
The Slavic languages are generally divided into East Slavic, South Slavic and West Slavic. For most comparative purposes, however, South Slavic does not function as a unit. Bulgarian and Macedonian, while quite similar to each other, are radically different from the other South Slavic languages in phonology and grammar. The phonology of Bulgarian and Macedonian is similar to East Slavic rather than their nearest Slavic neighbor Serbo-Croatian (suggesting an early East–West divide across the whole Slavic territory, before the incursion of Hungarian and Romanian speakers). In grammar, Bulgarian and Macedonian have developed distinctly from all other Slavic languages, eliminating nearly all case distinctions (strongly preserved elsewhere), but preserving and even strengthening the older Indo-European aspectual system consisting of synthetic aorist and imperfect tenses (largely eliminated elsewhere in favor of the new Slavic aspectual system).