The Roll of the Kings after the Introduction of Christianity is the most accurate part of LGE. For the most part, these kings are familiar to us from other sources. It should also be pointed out that whereas the first eight books of LGE are usually regarded as part of the Early Mythological Cycle, the last two books are properly assigned to the Historical Cycle.

The Roll of the Kings before the Introduction of Christianity contains much that is of interest to historians, but a lot of it is confused and bowdlerised. For example, the story of Tuathal Techtmar, who is depicted as a High King of Ireland in the early second century of the Christian era, is thought to be another version of the Goidelic invasion, Tuathal Techtmar being in reality the historical antecedent of Éremón.

Mug Nuadat, Éber's real antecedent,would then be similarly displaced.

Of the Bolgic and Laginian invasions in the stories of two other kings, Lugaid mac Dáire and Labraid Loingsech. These bowdlerisations may have been politically motivated: by providing the pre-Gaelic peoples of the island with pedigrees going back to Míl, the Gaels hoped to deny them any prior claim to the country, and so justify the Gaelic conquest.