The Dorian invasion (or Dorian migration) is an ancient Greek myth and discredited archaeological hypothesis describing the movement of the Dorian people into the Peloponnese region of Greece. According to the myth, the Dorians migrated from central Greece shortly after the Trojan War and populated most of the southern Peloponnese, particularly the regions of Laconia, Messenia and the Argolid. The myth became combined with that of the Return of the Heracleidae, such that the descendants of the hero Heracles were imagined to have led the Dorians and founded the ruling lines of several Dorian cities, including Sparta. The myth probably emerged during the Early Iron Age as part of a process of ethnogenesis between cities claiming Dorian ancestry. In the fifth century BCE, it gained greater prominence through its use to promote unity among Sparta's Peloponnesian allies, and to differentiate Sparta from its rival Athens, believed to be of Ionian heritage.
In 1824, the German antiquarian Karl Otfried Müller published The Dorians, in which he argued that the Dorians were a northern, Indo-European people who invaded Greece and subjugated the Peloponnese. Müller's views gained general scholarly acceptance throughout the remainder of the nineteenth century and into the twentieth. The Dorians were credited with introducing new forms of material culture and destroying the Mycenaean palaces, though this created conflicts between the interpretative narrative, the mythological tradition, and the archaeological evidence. The Dorians also became associated with the Sea Peoples, believed to have destroyed several Near Eastern sites at the end of the Bronze Age. During the first half of the twentieth century, scholars attempted to find archaeological and linguistic evidence of the Dorian invasion and to trace its route, though these efforts proved largely unsuccessful.