Unlike the myths of Greece or Rome, which were often written down in epic poems, Irish mythology was originally a spoken tradition. For centuries, trained storytellers, known as filí and seanchaithe, passed down a huge collection of tales from one generation to the next. These stories were the heart of Irish culture, explaining the world, celebrating heroes, and recording family histories.

It wasn't until the Middle Ages that Christian monks began writing these stories down. Because of this, many of the tales we have today are a blend of ancient pagan beliefs and a newer Christian perspective. This mix makes Irish mythology unique, full of magic, gods, and heroic deeds, but often with a monk's note or a Christian moral tucked inside.

To make sense of it all, scholars have grouped the myths into four major collections called "cycles."

Each cycle focuses on a different era or set of characters, but together they tell the legendary history of Ireland from its very beginnings.

The first and oldest collection is the Mythological Cycle. These are the foundational stories of Ireland. They tell of the world's creation and the series of invasions that supposedly settled the island. It’s a history not of ordinary humans, but of divine and supernatural beings who fought for control of the land.

At the heart of this cycle are the Tuatha Dé Danann, which translates to the “people of the goddess Danu.” They are a race of god-like figures with mastery over magic, who arrive in Ireland and establish a new order. Their stories are not just about grand battles; they explain the origins of Ireland’s hills, rivers, and ancient monuments. This cycle sets the stage for everything that comes after, creating the supernatural landscape where later heroes and kings would live out their destinies.

Following the age of gods, the other cycles shift focus to the world of mortals, though the supernatural is never far away.

These later cycles are filled with the exploits of human heroes and the politics of ancient kings. But the legacy of the Mythological Cycle is always present. The Otherworld, a realm inhabited by the Tuatha Dé Danann and other spirits, often intersects with the human world, influencing events and testing the courage of heroes. Understanding the Mythological Cycle is the key to unlocking the rest of this rich, interconnected world.