When Did The Empire Of Ancient Greece Begin?

The first official united greece recorded was during philip and his son alexanders time(337bc - 323bc).
Before that greece was divided to city states which constantly fought each other and would only unite(not all of them, like thebes which allied with persians) when they faced a barbarian threat (persia)
to be more accurate it began after the league of corinth or as historians refer "the first hellenic league" where all greek states voted philip to be the hegemon of greece and defender of hellenism, only spartans didnt vote philip as they always thought that the leader of greeks should be a spartan.
After alexanders death the states again divided and there were several kingdoms(macedonia, laconia, aitolia, akarnania, athenian league, Pontes, epirus, kingdom of Lysimachus) and many other hellenised kingdoms like egypt of ptolemy and seleucid empire)
the eventually started to fight against each other again and romans took the chance beating them easily.
Although many historians blame the last king of macedonia for this Perseus for his inability to handle the battle of pydna against romans although he was in advantage position.
Later a young man claiming to be the son of perseus rose an army in Peloponnese but was beaten by romans, and this was the end os hellenic empire.