The texts written during this era exhibit linguistic features of the vernaculars of the First Bulgarian Empire. Old Church Slavonic spread to other South-Eastern, Central, and Eastern European Slavic territories, most notably Croatia, Serbia, Bohemia, Lesser Poland, and principalities of the Kievan Rus' while retaining characteristically South Slavic linguistic features. It spread also to not completely Slavic territories, like those between the Carpathian Mountains, the Danube and the Black sea.