The Malagasy language is of Malayo-Polynesian origin and is generally spoken throughout the island. The numerous dialects of Malagasy, which are generally mutually intelligible, can be clustered under one of two subgroups: eastern Malagasy, spoken along the eastern forests and highlands including the Merina dialect of Antananarivo, and western Malagasy, spoken across the western coastal plains. The Malagasy language derives from the Southeast Barito languages, with the Ma'anyan language being its closest relative, incorporating numerous Malay and Javanese loanwords. French became the official language during the colonial period, when Madagascar came under the authority of France. In the first national Constitution of 1958, Malagasy and French were named the official languages of the Malagasy Republic. Madagascar is a francophone country, and French is mostly spoken as a second language among the educated population and used for international communication.