Although some fragments of texts produced within Ghulāt communities and dating from the end of the second or—perhaps more likely—the early third Islamic century are available, they focus almost entirely on a handful of doctrinal themes: creation myths and cosmology; the world of shadows (aẓilla); transmigration (tanāsukh) and the hierarchy of being; the divinity of certain human beings; and the esoteric interpretation of religious duties. Almost all other historical data on the early Ghulāt is drawn from external sources: above all a handful of Imāmī-Shīʿī and Muʿtazilī heresiographies, supplemented with sporadic information from the major historians. To some extent, the historians’ information can be traced back to the sources they cite openly. The material in the heresiographies is, however, of uncertain origin. Although many more heresiographies have become available, scholarship has hardly addressed the question of its provenance in over 60 years. There is also another body of material that has received even less attention: that available in Imāmī rijāl- and ḥadīth-works. This paper will briefly give an overview of the different bodies of material on the Ghulāt that are found in the histories and the heresiographies and comment on their perspective and likely provenance, before offering an isnād-based analysis of the origins and transmission of the relatively large number of reports on the Ghulāt preserved in Abū ʿAmr al-Kashshī’s (fl. mid-fourth/tenth century) Rijāl.