Which emperor divided the empire into greek-speaking east and latin- speaking west?

Answer 1

There was no Roman emperor who divided the empire into Greek speaking east and Latin speaking west. As far as languages go, Greek was spoken all over the empire as it was the lingua franca of the ancient world. As far as the "western" and "eastern" empires, they were inventions of historians. The Romans considered everyone in the empire Roman, no matter where they lived.