This map shows the extent of the Persian Empire in around 500 B.C. under the Zoroastrian Darius, third Achaemenid king of kings.
Persian Empire Map - 500 B.C.
The Historical Atlas by William R. Shepherd, 1923.
The Persian Empire in the time of Darius I extended to the African areas of Egypt and Libya to the south and west, Macedon and Thrace to the North and west, and to the Indus River in the East. Darius the Great was one of the kings the Greeks faced in the Persian Wars. The map is from the Perry-Castañeda Library