Ancient Irish refers to the early inhabitants and cultures of the island of Ireland before the arrival of Christianity. This period is characterized by the use of the Irish language, which evolved from the Goidelic branch of the Celtic languages. The society was organized into tribes, and they practiced agriculture, hunting, and gathering. The ancient Irish are known for their rich mythology and oral traditions, which include tales of legendary figures like Cú Chulainn and Fionn mac Cumhaill. They also created impressive stone structures, such as megalithic tombs and ring forts, which reflect their advanced understanding of architecture and community organization.