The Armenian language dates to the early period of Indo-European differentiation and dispersion some 5000 years ago, or perhaps as early as 7,800 years ago according to some recent research.
Armenian is regarded by some linguists as a close relative of Phrygian. Many scholars such as Clackson (1994) hold that Greek is the most closely related surviving language to Armenian. The characteristically Greek representation of word-initial laryngeals by prothetic vowels is shared by Armenian, which also shares other phonological and morphological peculiarities of Greek. The close relatedness of Armenian and Greek sheds light on the paraphyletic nature of the Centum-Satem isogloss. Armenian also shares major isoglosses with Greek; some linguists propose that the linguistic ancestors of the Armenians and Greeks were either identical or in a close contact relation. However other linguists including Fortson (2004) comment "by the time we reach our earliest Armenian records in the 5th century A.D., the evidence of any such early kinship has been reduced to a few tantalizing pieces."
W. M. Austin in 1942 concluded that there was an early contact between Armenian and Anatolian languages, based on what he considered common archaisms, such as the lack of a feminine, the absence of inherited long vowels and the centum character.
The Classical Armenian language (often referred to as Grabar, literally "written (language)") imported numerous words from Middle Iranian languages, primarily Parthian, and contains smaller inventories of borrowings from Greek, Syriac, Latin, and autochthonous languages such as Urartian. Middle Armenian (11th–15th centuries AD) incorporated further loans from Arabic, Turkish, Persian, and Latin, and the modern dialects took in hundreds of additional words from Modern Turkish and Persian. Therefore, determining the historical evolution of Armenian is particularly difficult because Armenian borrowed many words from Parthian and Persian (both Iranian languages) as well as from Greek.
The large percentage of loans from Iranian languages initially led linguists to classify Armenian as an Iranian language. The distinctness of Armenian was only recognized when Hübschmann (1875) used the comparative method to distinguish two layers of Iranian loans from the true Armenian vocabulary. The two modern literary dialects, Western (originally associated with writers in the Ottoman Empire) and Eastern (originally associated with writers in the Russian Empire), removed almost all of their Turkish lexical influences in the 20th century, primarily following the Armenian Genocide.