Historically, the name Armenian has come to internationally designate this group of people. It was first used by neighbouring countries of ancient Armenia. The earliest attestations of the exonym Armenia date around the 6th century BC. In his trilingual Behistun Inscription dated to 517 BC, Darius I the Great of Persia refers to Urashtu (in Babylonian) as Armina (in Old Persian; Armina (    ) and Harminuya (in Elamite). In Greek, Αρμένιοι "Armenians" is attested from about the same time, perhaps the earliest reference being a fragment attributed to Hecataeus of Miletus (476 BC). Xenophon, a Greek general serving in some of the Persian expeditions, describes many aspects of Armenian village life and hospitality in around 401 BC. He relates that the people spoke a language that to his ear sounded like the language of the Persians.

Answer this question, if possible (if impossible, reply "unanswerable"): How long ago has the term 'Armenia' been used?
around the 6th century BC