Comparing the Linear B tablets discovered on the Greek mainland, and noting that certain symbol groups appeared only in the Cretan texts, Ventris made the inspired guess that those were place names on the island. This proved to be correct. Armed with the symbols he could decipher from this, Ventris soon unlocked much text and determined that the underlying language of Linear B was in fact Greek. This overturned Evans's theories of Minoan history by establishing that Cretan civilization, at least in the later periods associated with the Linear B tablets, had been part of Mycenean Greece.