Belarusian is an Eastern Slavonic language with about 7.5 million speakers in Belarus. It is closely related to Russian and Ukrainian. Most Belarusians are bilingual in Belarusian and Russian.
The country now known as the Belarus was part of the Grand Duchy of Lithuania from the mid 13th century until the end of the 18th century. An archaic form of Belarusian known as “Old Belarusian” was the offical language of the Grand Duchy and and was initially written with the Cyrillic alphabet.
Due to the domination of the Greek Orthodox Church in the region, the written form of Belarusian was heavily influenced by Church Slavonic, the liturgical language of the Orthodox church.