Proto‑Indo‑Europeans were a prehistoric culture who lived between roughly 4000 and 2500 BCE in the Pontic–Caspian Steppe, an area covering much of modern‑day Ukraine and southern Russia. Although no written texts survive from this society, scholars have traced echoes of their beliefs across later ancient religions. By comparing myths, languages, and ritual structures, researchers have reconstructed aspects of the Proto‑Indo‑European religion—a belief system whose core themes resonated for millennia and influenced cultures across vast distances.
As horse domestication advanced and wheeled vehicles emerged, Proto‑Indo‑European groups began to migrate outward from the steppe. One such migration route likely carried people from the Pontic–Caspian region through the Lower Danube (modern‑day Moldova and Romania), across the Balkans, and into Greece. There, they encountered and mixed with the existing Neolithic populations. This cultural blending is reflected in changes in architecture, pottery styles, and burial customs. Over time, the number of fortified hill settlements grew and social hierarchies emerged, giving rise to the Mycenaean Greek civilisation. The religion of the Mycenaeans, in turn, developed from this blend of cultures, retaining clear traces of Proto‑Indo‑European tradition.
A prominent example of this inheritance is the Greek god Zeus. His name derives from the Proto‑Indo‑European Dyēus, the “sky father,” yet Zeus also embodies the role of a storm or thunder god—two beings that remain distinct in many other Indo‑European cultures. The thunder god aspect of Zeus’ origin connects him to a recurring mythological story: the Dragon Slayer. Across numerous Indo‑European belief systems, a thunder deity battles and overcomes a serpent or dragon. In Greek myth, Zeus defeats Typhon to secure supremacy over the cosmos. Norse mythology tells of Thor’s confrontation with Jörmungandr during Ragnarök, leading to both of their deaths . In the Vedic tradition (the foundation of Hinduism), Indra wields a thunderbolt to slay the Vṛtra a human like serpent said to be personification of draught. Slavic and Hittite belief systems mirror this great tale.
Another repeated theme that seems to have spread from the PIE peoples is that of divine twin heroes who are often associated with horses. In Greek mythology Castor and Pollux were twin horsemen, who were the patrons of sailors. They were represented in the Zodiac calendar as Gemini (Latin for Twins). Some believe that the Zodiac calendar was adopted by the Greeks from the Babylonians, but then adapted to fit in with their originally PIE beliefs.

While Proto‑Indo‑European themes shaped much of Mycenaean belief, the Mycenaeans also absorbed significant religious influence from the Minoans of Crete. The Minoans had lived on Crete for millennia and had developed religions and mythologies of their own.
Whilst the descendants of PIE religions tended to be male dominated, Minoan religion was primarily based around female deity worship. This can be seen in Minoan art where a central Mother Goddess figure is featured along with a Snake Goddess and Animal Mistress. It is likely that these characteristics were adopted by the Mycenaean Greeks as Rhea (mother of the gods), Athena; who is often represented with snakes, she turned the priestess Medusa into a snake-haired gorgon, and Artemis the Mistress of Animals.
Bulls also played a central ritual role in Minoan religion, often featured in pottery and art with bull horns used as sacred symbols. The Greeks reinterpreted this imagery through myth, most famously in the story of Theseus and the Minotaur. The Labyrinth described in that tale is widely considered a mythologised memory of the complex architectural layout of the Palace at Knossos on the island of Crete.

Mycenaean Greek religions developed over time from a blending of cultures. I’ll explore further into the building blocks of Greek mythology and other religions around the globe, any many cases tracing them back to Proto-Indo-European beliefs.