Who conquered the Persian emprie?

The Persian Empire was primarily conquered by Alexander the great in the 4th century BCE. After a series of decisive battles, including the Battle of Granicus, the Battle of Issus, and the Battle of Gaugamela, Alexander defeated the Persian king Darius III. Following Darius's defeat, Alexander continued to expand his empire into Persian territory, ultimately leading to the fall of the Achaemenid dynasty.