Ancient Greece (Ancient Greek: Ἑλλάς, romanized: Hellás) was an ancient civilization existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity (c. 600 AD), comprising a loose collection of culturally and linguistically related city-states and regions, primarily centered in the northeastern area of the Mediterranean Sea. Prior to the Roman period, most of this area was officially unified only once, from 338 to 323 BC under the Kingdom of Macedon. In Western history, the era of classical antiquity was immediately followed by the Early Middle Ages and the Byzantine period.
Scholars mark Ancient Greece as beginning with Mycenaean Greece, which declined during the Bronze Age collapse c. 1100 BC. Three centuries later, Greek urban city-states, or poleis, began to form in the 8th century BC, ushering in the Archaic period and Greek colonization of the Mediterranean Basin. This was followed by the intellectual flourishing of the Classical period of Ancient Greece, from the Greco-Persian Wars to the death of Alexander the Great in 323 BC, which included the Golden Age of Athens, the Peloponnesian War between Athens and Sparta, the short-lived Spartan and Theban hegemonies, the creation of the Hellenic league led by Philip II of Macedon and the subsequent conquest of Persia's Achaemenid Empire by his son Alexander the Great. Alexander's territorial conquests led to the spread of Ancient Greek culture into northern Africa and western Asia: the Hellenistic period, ending c. 30 BC, when the Ptolemaic kingdom of Egypt, centred in Alexandria, was annexed by Rome.
Classical Greek culture, especially Greek philosophy, had a powerful influence on Ancient Rome, which propagated variants of it throughout the Mediterranean and much of Europe. For this reason, Classical Greece is generally considered the cradle of Western civilization, the seminal culture from which the modern West derives many of its founding archetypes and ideas in politics, philosophy, science, and art.