Since when have there been different dialects and languages in the world?

Les teaches that the Greek word for tongues does not mean unknown gibberish; it means a language, an understandable language. He explains that ever since the Tower of Babel, there have been all kinds of dialects and languages throughout the then-known world. The Jews had been out in a dispersion: the ten tribes went into captivity into Syria about 775 B.C. and never really came back as tribes, which is why some call them the lost tribes. About 150 years later, Judah and Benjamin were taken captive to Babylon, and only a few thousand returned after the 70 years; the rest were assimilated into the Middle East. Les compares this to immigrants in America: their children often learned the parents' native language first, becoming bilingual, and only after two or three generations did they lose that mother tongue and pick up English.