Amlash is one of the most important parts of Guilan Province in northern Iran. It has endured unending political and military turmoil due to its special geopolitical and geostrategic position, during the early and middle Islamic eras. The establishment of numerous castles in the area is one of the manifestations of this state of affairs during that period. This study, based on library and field study, is aimed at analyzing the factors that might have led to the formation of the castles. The library studies included a review of literature on military castles and fortresses for an analysis of the factors that might have contributed to the castles in the Amlash region. The field studies included direct observation of the locating, photographic imaging, and numerical measurement and topographical features of those castles.
