Archaeologists working in Turkey say they've found evidence of a forgotten language dating back more than 2,500 years to the time of the Assyrian Empire.

Researchers from Cambridge University in Britain, working at the probable site of the ancient Assyrian city of Tushan, said the language may have been spoken by deportees originally from the Zagros Mountains, on the border of modern-day Iran and Iraq.

Under a policy widely practiced across the Assyrian Empire, those people may have been forcibly moved from their homeland and resettled in what is now southeast Turkey, the researchers said.

"It was an approach which helped [Assyrians] to consolidate power by breaking the control of the ruling elite in newly-conquered areas," Cambridge researcher John MacGinnis said. "If people were deported to a new location, they were entirely dependent on the Assyrian administration for their well-being."

The evidence for the language they spoke comes from a single clay tablet that survived the fire that destroyed a palace in Tushan, inscribed with cuneiform characters that list the names of women who were attached to the palace and the local Assyrian administration.

"Altogether around 60 names are preserved," MacGinnis said. "One or two are actually Assyrian and a few more may belong to other known languages of the period, such as Luwian or Hurrian, but the great majority belong to a previously unidentified language.

"We know from existing texts that the Assyrians did conquer people from that region [western Iran.] Now we know that there is another language, perhaps from the same area, and maybe more evidence of its existence waiting to be discovered."