: In most works approaching Premodern historiographical phenomena there is a remarkable silence about Seanchas, an Irish tradition related to old tales, memory, history, historiography genealogy and traditional law. The main purpose of this article is to analyze this issue, pointing out Seanchas is a conditio sine qua non to the comprehension of both Irish History and Historiography from Early Christian to Modern Ireland. Therefore, any attempt to understand Premodern and Early Modern European historiography should also consider this Irish contribution.