Alexander added to what other people did to create history such as his father.
He established many new colonies and cities, many of which were named after him. He adopted some Persian dresses and customs, married Bactrian and Persian princesses, and thousands of his Macedonians and Greeks wed to Persian women.
Many Greeks had already gone over into the Persian empire to serve as soldiers, traders, and doctors. Alexander trained and used Persians in his army which other people have done. Greece was already undergoing population pressures and a rising standard of living.
Philip of Macedon had created the phalanx and started building and empire.
Philip conditioned and educated Alexander to be his heir. Alexander just continued what Philip had started.
Little had been done to organize his empire; no permanent institutions were created to govern it. The empire would go to the strongest. Greece ruled the near east politically for three hundred years and culturally for one thousand. Absolute Monarchs ruled after he died, and he unity Alexander had created politically fell apart.