The -nth- and -ss- (or -tt-) place names occur both on Crete and on mainland Greece, and also in Asia Minor (e.g., Halicarnassus). Sometimes it is -nd- instead of -nth-.
Also on both sides of the Adriatic, and some on the Tyrrhenian side of Italy, Sicily, west shore (and inland) of the Black Sea, the Aegean, Cyprus, and throughout Anatolia. (found the scan).