Abstract The article examines the origins of the alternative history genre within the context of the development of counterfactual thinking, historiography and literary practice. The relevance of the study is determined by the growing scholarly interest in modeling historical reality and reconsidering the principles of historical causality in the humanities. The aim of the research is to identify the foundations of alternative history and to outline the stages of its formation as an independent literary genre. The methodological framework draws on the concept of counterfactual history, possible worlds theory and narrative approaches of postmodernism. The analysis shows that elements of alternative modeling can already be found in ancient historiography; these elements were further developed in the early modern philosophy and later in nineteenth-century literature. Particular attention is paid to early literary forms of alternative history and to the consolidation of the genre in the twentieth century. The findings suggest that alternative history emerges as a form of conceptualizing historical variability and gradually evolves into a stable literary practice.