Why is Armenian classified as its own branch of the Indo-European language family?

The Armenian language is classified as a separate, independent branch of the Indo-European language family because it does not belong to any of the other established subbranches.12

Historically, Armenian was erroneously considered a dialect of Iranian due to the significant linguistic impact of Persian on its vocabulary. However, modern linguistic analysis confirms its status as a distinct branch.12

Linguistically, Armenian occupies a unique position because it exhibits characteristics of both major groupings of Indo-European languages:
* It belongs to the satem group, as it shows the characteristic shift where palatal stops became fricatives.3
* It simultaneously preserves some features of the centum group by retaining occasional palatal stops as k-like sounds.3

Furthermore, the language has undergone a unique "consonant shift" throughout its history—a process of sound change that, while independent of other language families, further distinguishes its phonological development from its Indo-European relatives.4