46Waddell, John, Joe Fenwick, and K. J. Barton. Rathcroghan: Archaeological and Geophysical Survey in a Ritual Landscape. Dublin: Wordwell, 2009. 210.
The author is confident that although the ceremonial use of Rathcroghan was principally in the late prehistoric Iron Age, that its significance would have extended into the start of the Christian era in Ireland in the fifth century CE. He suggests that the "various mounds span one or even two millennia." (p. 222)