Christianity was introduced into Ireland in the 5th century, but the majority of the population continued to be buried in ancestral or familial burial places until the early 8th. This paper examines evidence for the introduction into Ireland in the 5th century of burial in long cists (and the possible source of this new rite in the fringes of Roman Britain); the insertion in the 5 th/6th century of small numbers of long cists and unprotected burials into prehistoric burial monuments, usually located in border territories; and in the 7th century the insertion of unprotected burials into similar monuments. The probable political rather than religious reasons for the continuation of this practice well into the Christian era are then examined and the motivation behind the abrupt cessation of the practice in the late 7th/early 8th century. As a result of church influence, the majority of familial or ancestral cemeteries were abandoned in the 8th century in favour of burial in church-associated cemeteries.