The dream of forming a Pan-Hellenic Empire by Athens was shattered by the rivalry of Athens and Sparta. Athens and Sparta were the two leading powers in the Ancient Greece. Most of the ancient Greek city states were allied with either Athens or Sparta. The end result of suspicion and rivalry between the two super powers led to the break up of war between both alliances in 431 BC. The war is fought near the Peninsula where Sparta was located and hence known as the Peleponnessian war.

The Persian wars and the formation of Delian League transformed Athens into a powerful nation. The members of the league were about 200 in number contributed money, ships, and men into the common pool. Spartans feared that Athens who headed the League would challenge the Spartan leadership in the Greek world. Their fears came true when Athens with its vast resources and maritime power began to show the imperialists designs by controlling the Greek city states. Many of the nearby free states became tributaries of Athens. The Spartans came to the conclusion that the Athenians had broken the Thirty Years Peace. The Athenians obstructed the freedom of the states in pursuing their own affairs and restricted their independence. This was against the spirit of the treaty.

In short, the imperialistic attitude of the Athens led to the Peloponnesian war.

Economic reason for the war was the trade relations of Athens with other Greek city states. Athens wanted to control eastern and western trade. When Athens tried to monopolize the trade, it created annoyance between Athens and Sparta. The final example of trade war can be seen in the Megarrian decree. The act of Athens is like today's modern economic sanctions. It forbade Megara to trade with the prosperous Athens. Sparta had taken this action on the part of Athens as a serious provocation.

The Social systems of Athens and Sparta were completely different. After the defeat of the Persians, Athens continued to follow democracy at home but oppression abroad. Athenians had freedom in politics as well as personal. There were ample opportunities for pleasure and leisure. The contradiction was that the same society which believed in democracy had suppressed the freedom of its allies and followed a policy of tributary system. Spartan society on the otherhand was completely in different. The nature of the Spartan society was military in nature. The slave population in Sparta or helots was continually looked upon with vigilance to prevent any slave uprisings. The slave revolts made the Spartan society to train their boys militarily from the age of seven. The Spartan society was completely opposite to Athenians. They were conservatives and kept a strict isolation.

Philip II, the father of Alexander, the great came to the throne of Macedonia at a difficult time. He faced the internal and external threats by following the policy of diplomacy. He freed the north western Macedonia by invading Illarians in 358 BC and brought all North Macedonia under his control. Philip II strengthened the Macedonian army by reorganizing it. He transformed the part time army into an efficient professional army. Philip II strengthened himself my making series of marriage alliances. He followed a policy of divide and rule. After the annexation of the North Macedonia, he turned towards the south. He carried on a continuous conquest of all the Greek city states. Philip won a great victory against Athens and allies in 338 BC. He threatened Persian Empire with an invasion but in the meantime, he was assassinated. Philip was succeeded by his daring son, Alexander, the great. He was the champion of Greece who tried to create a Pan Hellenic Empire by expelling Persians and unified Greece.

The death of Philip II caused many insurrections in northern and southern Greece. Alexander crushed those insurrections hoping that it would not be repeated. Soon another major revolt broke out and spread to all parts of Greece. Alexander crushed and burned Thebes. After crushing the opposition in Greece, Alexander set out to conquer the whole of Asia. Alexander defeated King Darius III in the Battle of Granicus. Alexander invaded and conquered coastal and central Asia Minor including the city of Gordium. In 333 BC, Alexander defeated in Darius III in the Battle of Issus. It was a great victory for the Macedonians. Darius himself fled leaving his family behind. It was followed by the siege and conquest of Tyre and Gaza. Alexander entered Babylon and conquered Egypt without any resistance in 331 BC. He built the city of Alexandria on the bank of the river Nile. It later became a major economic and cultural center. Alexander put the Persian Empire to an end with the defeat of Darius in the Battle of Gaugamela. In 327, Alexander marched towards India and defeated king Porus near the river Hydaspes. After this victory, the Macedonians refused to move forward and Alexander had to return to Persia, where he died.

The spread of Hellenism can be divided into two periods. One period was during the time of conquest of Alexander and other after his death. During the conquest, Alexander founded some cities like the city of Alexandria. It helped spread Greek culture to the east. Alexander really tried to create a fusion of Greek and Persian culture by imitating some aspects of Persian culture. After the death of Alexander in 323 BC, the empire was divided into four kingdoms and the successor kings refused to follow the foot steps of Alexander. They had placed Greeks in positions of power in their respective regions and it helped the spread of Greek culture. At the same time, they allowed natives to follow their culture and religion. Greek way of religion was followed in native conquered lands. The Greek literature spread in Persian regions as a consequence of the spread of Greek language. The library at Alexandria became a center of learning and literature. Greek influence was also seen in coinage too. In the same way, Greek culture influenced the Middle East and the ideas of the east spread to the west. When Alexander broke the political barrier, trade also flourished. The common culture Alexander created led to the development of western civilization and spread of Christianity