After 1350 or so, logical traditions began to crystallise, often on a regional basis. Recent studies by El-Rouayheb (2010b) and Ahmed (2012) have provided preliminary sketches of the seven or so centuries of logical activity. Especially El-Rouayheb (2010b) makes it clear that we cannot assume that there is a point at which original work stops and the tradition begins simply to restate ancient results. It is true that much of the later material is, unlike the bulk of the thirteenth-century material, presented as commentary. There is a temptation to conclude from this that there was a decline in logical studies in the realms under Muslim control that corresponds with the sixteenth-century decline of the subject in early modern Europe; such a conclusion is seemingly supported by a tradition of scholarship devoted to a luxuriation of layered commentary on a five hundred year old primary text. But genre by no means dictates content, and we often find original work presented in this  way.[16]