Original sentence: Famous examples are Alexander the Great and his empire, the Mongol Empire, and the British Empire, which all encompassed substantial portions of the then known world; in the case of the British, a quarter of the world's surface
Edited sentence: Famous examples are Alexander the Great and his empire, the Mongol Empire, and the British Empire, which all encompassed excessively large amounts of the known world; in the case of the British, a quarter of the world's surface