The Persians:
Darius III (also known as Codomannus) was the son of Arsames and Sysigambus. He was of high birth and had a reputation as a great soldier as a young man. Darius III was the last king of Persia. He took to the throne in 336BC when he was 45 years old.
Geography:

(Persian empire during the rule of Darius)
The formation of the Persian Empire started in 550BC and is said to be the “largest the ancient world had seen” . The empire stretched from Egypt to Central Asia before it was taken over By Alexander the Great, the king of Macedonia and now is modern day Iran. The Empire was divided into 20 provinces each one governed by a satrap (local ruler). When Darius III died, Alexander’s fight for the empire wasn’t over. He had to fight and take each of the provinces by force this shows how stable the empire was during Darius’ rule.
Military:
Cyrus left Darius with a very strong land-army before he died. The Persian army consisted of an Infantry and a cavalry (the cavalry were usually on horses). The army traditionally wore armour called “scale armour” which was small scale like plates of bronze woven onto a leather shirt, this was commonly worn by the wealthier infantrymen. The Persians military navy was formed by Darius the great. This strengthened the Persian army because this allowed the Persians to fight on sea as well as land.
Macedonians:
Alexander III was the king of Macedonia. He was the son of Phillip king of Macedonia and Olympias the princess of Epirus. As a young man Alexander proved himself very capable to his father and to the entire of Macedonia, first when he was 12, he was the only one who managed to tame a horse that no one else was able to ride. According to Plutarch to this his father said 'O my son, look thee out a kingdom equal to and worthy of thyself, for Macedonia is too little for thee' " . Alexander proved himself capable again when he was ruled over Macedonia in his