The setting of the Táin Bó Cúailnge has traditionally been identified as the first century A.D. The earliest extant manuscript of any version of the work was written in the early twelfth century in the great monastery of Clonmacnoise overlooking the Shannon River. Sometime between these two dates, the Táin Bó Cúailnge came into existence.
It has been a basic assumption of Irish literary studies that the Táin Bó Cúailnge was written to be the Aeneid of Ireland. Nevertheless, despite continuous references to the characters and events of the Táin Bó Cúailnge, it is probably true that the stories of the Irish hero Finn Mac Cumhghaill (Finn Mac Cool), his son Oisín, and his warrior band, the Fianna, were more popular until the nineteenth century. Then, Irish nationalism interacting with contemporary scholarship began to look to the Táin Bó Cúailnge as the major source for a sense of Irish identity. National and cultural worth was judged against the classical past and the dominant English language culture. It was important that Ireland had a vernacular epic.
The Irish literary revival at the turn of the nineteenth and twentieth centuries introduced the Táin Bó Cúailnge to a world audience. Lady Augusta Gregory, patroness of the young W. B. Yeats, published retellings of the stories clustered around the hero of the Táin Bó Cúailnge, Cúchulainn. Yeats wrote a series of plays based on the stories of Cúchulainn and Deirdre (Dierdriu) and the Táin Bó Cúailnge entered the western literary heritage.