Because the people of the Mediterranean were as imprecise as westerners are when referring to other people. They called "franks" any people in the west that did

Because the people of the Mediterranean were as imprecise as westerners are when referring to other people. They called "franks" any people in the west that didn't speak Greek. In the same way as many today call arabs any people that are Muslim even if thet are Turks or Iranians