In Macedonia, a young man called Alexander succeeded his murdered father Philip II. He was then a 20-year-old young man.

Alexander the Great launched a war against Persia. He met the Persians led by Darius III at Issus where he won a great battle.

Alexander the Great

Now all the way to Egypt was open for him. So he marched his army to Pelusium were the Persian satrap surrendered.
He then arrived at Memphis and was cordially welcomed. Actually the Egyptians regarded him as a savior from the cruelty of the Persians. It's where he was crowned as a Pharaoh in Memphis. Moreover, the Egyptians considered him a divine being or God's son.

Alexander the Great headed north and in a place near Rhakotis he planned for the future city that bore his name: Alexandria.
Alexandria, the first to hold Alexander's name, was never built in Alexander's life. Later it would become the new capital of Egypt and the cultural threshold of the Mediterranean nations.

For many centuries after its founding, Alexandria shed light over the humanity, as a cradle of science, trade, culture, philosophy, medicine and policy.

Alexander then headed to Siwa Oasis where he was greeted by Amun priests and given the title of son of Amun. Afterwards, he left to Memphis and there he managed to form the administration that was to rule Egypt. He carried out restoration plans to the buildings that were devastated by the Persians. And it was from there that he planned for his Asian conquest.
Leaving rulers in Egypt, Alexander left to his successful campaigns to form a great empire.

Unfortunately he died of fever in Babylon. He was at the age of 38 when he died.
Alexander's death was a surprise that resulted into a complicated situation. This is because Alexander didn't set administrative rules, as he was busy enough with his military campaigns. And of course he didn't leave a legitimate heir.

It was Perdiccas, a senior general of Alexander, who was the de facto regent. A group of generals, known as the diadochi (the followers) contended each other over the post motivated by their personal motives.
Perdiccas, as a result, called for a meeting among those diadochi. The result was the division of Alexander's empire among his generals.
Despite the compromise, wars erupted between them in a race to annex more lands to their kingdoms.

Ptolemy I, the then-satrap of Egypt took over Egypt declaring it as his monarchy.
Ptolemy secured his rule eventually after he annexed Palestine and lower Syria to his kingdom. Thus the new empire of the Ptolemies started.