Whether or not Mandaeans emigrated from Palestine to Mesopotamia, as the supporters of the Western origin theory suggest, or if Mesopotamia was the area from which the group emerged, as proponents of the Eastern Origin theory maintain, it remains true that the area between Wasit and Basra—noted for its sweet water lakes, and known by early Islamic geographers simply as "the Marshes"—was the region which saw their earliest settlement, beginning with the pre-Islamic era and extending to the present day. It was within this lush and aquatic ecosystem that the Mandeans’ religious beliefs took shape, with their emphasis on the sanctity of flowing water and its identification with vitality and life itself. Interest in the Mandeans and their religious beliefs has been largely restricted to Orientalists, with very few Arabic sources dealing with this topic. The author intends to use this article as part of a remedy of this problem, and does so in two distinct sections. The first section is devoted to a literature review covering the most important contributions to the scholarship surrounding the Sabean Mandeans. The second section of the study concerns the ethnic origins of the Sabean Mandeans, and the influences which shaped their religious beliefs, based on the author’s reading of their sacred texts. It further surveys both the Eastern and Western Origins theories, examining in detail the difficulties which plague both and the major milestones in the controversy that engrosses these two theories.