Clann O'Reilly is a prominent Gaelic Irish family that traces its lineage back to the ancient kings of Ireland. The family is primarily associated with the region of County Cavan and has a rich history that includes involvement in local governance and military affairs throughout the centuries. The O'Reillys were known for their leadership and influence, particularly during the Middle Ages. They played a significant role in the political landscape of Ulster and were involved in various conflicts and alliances that shaped the history of the area. Today, the legacy of Clann O'Reilly continues to be celebrated in Irish culture.