The common proto-language of the Indo-Iranian languages is the Proto-Indo-Iranian language, which has been reconstructed. The oldest well-attested Indo-Iranian languages are Vedic Sanskrit, Older and Younger Avestan and Old Persian (ancient Iranian languages).
Phrygian: language of the ancient Phrygians. Very likely, but not certainly, a sister group to Hellenic. Sicel: an ancient language spoken by the Sicels (Greek Sikeloi, Latin Siculi), one of the three indigenous (i.e. pre-Greek and pre-Punic) tribes of Sicily. Proposed relationship to Latin or proto-Illyrian (Pre-Indo-European) at an earlier stage.