A close observation of Iran-Iraq war films in the Iranian society reveals that their genres have shifted in the course of the society’s evolution. This questions the category-based principles of genre we have known so far in literature concerning film theory and necessitates a new conceptualization of genre, which can be realized with the aid of Niklas Luhmann’s social systems theory. This theory abandons categorization in favor of functional differentiation and helps us observe Iranian war movies in their societal context. By taking a close look at the function of film in the society as one of the mass media, and through locating the concepts of memory, reality, identity and genre in Luhmann’s theory, I shall find a pattern in the mentioned genre shift which is in turn punctuated by the Iranian society’s different stages of evolution. To do so, I shall rely on a qualitative, analytical and critical method.