Page "Poseidon" Paragraph 9

Given Poseidon's connection with horses as well as the sea, and the landlocked situation of the likely Indo-European homeland, Nobuo Komita has proposed that Poseidon was originally an aristocratic Indo-European horse-god who was then assimilated to Near Eastern aquatic deities when the basis of the Greek livelihood shifted from the land to the sea, or a god of fresh waters who was assigned a secondary role as god of the sea, where he overwhelmed the original Aegean sea deities such as Proteus and Nereus.

Conversely, Walter Burkert suggests that the Hellene cult worship of Poseidon as a horse god may be connected to the introduction of the horse and war-chariot from Anatolia to Greece around 1600 BC.