The present article explores the historical sections of Grotius's De iure praedae Commentarius bearing the following fundamental but very important questions in mind: What did Grotius actually know about the Portuguese Estado da Índia at the time of drafting the treatise between 1604 and 1606/8? What did he know about the Luso-Asian trading regime or Asian trading practices at large? Using the published correspondence of Grotius, archival documentation, manuscript fragments as well as unpublished reading notes and drafts, a case will (...) be made that he had in fact few sources at his fingertips. This insight serves fundamentally to refute older assumptions, expounded notably by Robert Fruin and C.H. Alexandrowicz, that the young Grotius conducted independent research in the VOC company archives, or had immersed himself with Asian maritime codes or commercial practices. (shrink)