There is a theroy that when a nation's language disappears, it means that the nation itself has vanished.

After Egypt was conquered by the Arab Empire, it began speaking Arabic, and the Egyptian language disappeared. Therefore, some people believe that although modern Egyptians are the descendants of the ancient Egyptians, the Egyptian people have already vanished, and today's Egyptians are actually Arabs. In contrast, after the Roman Empire moved its capital to Greece, it gradually replaced Latin with Greek. Later, when the Roman Empire was destroyed by the Turks, the Greeks did not start speaking Turkish but retained their Greek language. As a result, the Greek people did not disappear.