5O'Kelly, Michael J., and Claire O'Kelly. Newgrange: Archaeology, Art, and Legend. London: Thames and Hudson, 1982. 35.
According to O'Kelly: "Most of the other writers attributed Newgrange to the Danes and influences were also invoked from Egypt, India, Ethiopia, Phoenicia, Celtic Gaul, and soon; in fact, almost any race under the sun was considered eligible save for the natives themselves."
It is ironic that the eighteenth-century authors could have considered that the Vikings might have constructed the monuments. As George Petrie put it in 1834, "That the Danes, far from being the erectors of the sepulchral mound at New Grange, and the others contiguous to it, were, on the contrary, the very first that violated them..." (Petrie, George, and D.J.S. O'Malley. "Aspects of George Petrie. V. An Essay on Military Architecture in Ireland Previous to the English Invasion." Proceedings of the Royal Irish Academy. Section C: Archaeology, Celtic Studies, History, Linguistics, Literature 72 (1834 (1972)): 262-63.)
The impetus to credit the ancient tombs of Ireland to other races may have derived from a conviction by the ascendency that the natives could not be capable of building these monuments. Also, according to David McGuinness,"...this speculative and uncritical approach begun in the first decades of the eighteenth century, combined with the new ideals of Romanticism, was responsible for the excesses of [Vallancey] that saw its close. All the way through to the 1830s, writings on the megalithic tombs of Ireland are dominated by a non-archaeological approach. The spurious philology and etymology of Rowlands, whereby the origins and purpose of megalithic tombs were derived from the meanings and connections of their local names, in conjunction with an almost scholastic obsession with the writings of the ancients and those of modem authors from Rowlands onwards, stifled the ability of most to examine the monuments in the field afresh and without preconceptions." (McGuiness, David. "Edward Lhuyd's Contribution to the Study of Irish Megalithic Tombs." The Journal of the Royal Society of Antiquaries of Ireland 126 (1996): 82.)
About the coins found buried at the monument which Lhuyd cites as evidence that Newgrange pre-dated the Danes, Carleton Jones wrote, "This is a practice that has been documented at ancient sites in Roman Britain and it is possible that the Newgrange offerings were made by visitors from Roman Britain. It is also quite possible, however, that the offerings were made by Irish returning home from raiding or trading excursions to Britain. Whoever made the offerings, it is clear that Newgrange was still a respected and powerful place in the landscape almost three millennia after it had been built." (Jones, Carleton. Temples of Stone: Exploring the Megalithic Tombs of Ireland. Cork: Collins, 2007. 249.)