After examining the most important, independent developments constituting Armenian as a separate language branch, it discusses those phonological, morphological, and lexical innovations that are shared with, in particular, Greek, Phrygian and Albanian. Armenians, a population in Western Asia historically inhabiting the Armenian highlands, were long believed to be descendants of Phrygian settlers from the Balkans. This "Balkan Theory" originated largely from the accounts of the Greek historian Herodotus, who observed that Armenians were armed in. The chapter assesses the phylogenetic position of Armenian within the Indo-European language family. Armenian phonology seems to have been greatly affected by Urartian, which may suggest a period of bilingualism.