"Uy ah ual ing ual ing wetail." (The enemy of my enemy is my friend)
If you are asking about what language is 'used' in the television series Stargate, then the answer is English. But if you are asking about what language is used 'on' the stargate device (the words written on it and the chevrons) then the answer is the Ancient's language.
Chinese
The Celtic language was spoken by the ancients in the regon, but the language spoken in Britain is not known. It was not recorded.
No. The Ancient Hebrews spoke Hebrew.
The language spoken in Athens during ancient times was Ancient Greek. Today, the official language of Athens is Modern Greek.
There is no record of the language(s) spoken by the ancient Beothuk people.
No one alive today knows how ancient Egyptian was spoken.
Latin
Uxmal is an ancient Mayan city in Yukatán, the language spoken there was the Mayan language.
Latin.
Latin.
The Greek language originated around 3,500 years ago in ancient Greece and began to be spoken by the ancient Greeks during the 2nd millennium BC.