Bulgarians are a Slavic people living in the region which, in ancient times, was called Moesia. The acquired their name from a Turkic or Finno-Ugric tribe which invaded Moesia in the 10th century AD. They are the descendants of ancient Thracian tribes, such as Moesi, Agrianes etc., of ancient Celtic tribes who founded the Tulis Kingdom in 270 BC, of Germanic tribes such as Gepids, Heruli and Goths, of Slavic tribes and of those Bulgarian invaders who originally inhabited a region east of Volga river.
In modern times, many Bulgarians speak a Southern Slavic language which has been deeply influenced by Medieval and Modern Greek, as well as - though in a lesser extent - by Osmanli Turkish. It has many traits in common with Slovenian and Croatoserbian, with which it can sometimes be mutually intelligible, although this is not true of its intelligibility with Western and Eastern Slavic languages.
See also: Bulgaria