“Explanation” is an important issue in the philosophy of history, science of history and historiography with its all types, models and patterns. It is responsible for expressing the rational relationship between the events, changes and historical developments on the one hand and the why and the how of them on the other hand. Paying attention to the Muslim historians’ methods and models of historiography reveals the origin of the thoughts and ideas pertaining to the explanation in relation with the history of Islam events. Examining different types of explanations can reveal the evolution of the explanation in the Islamic historiography. It developed significantly due to the scientific, intellectual, cultural, political and social changes and advancements. Implementing an analytical method, this article tried to investigate different types of explanations in the works of prominent historians like Tabari, Masudi, Moqadasi, Miskawayh, Ibn Kasir and Ibn Khaldun from the fourth to the eighth centuries. The results revealed that explanation evolved towards rational explanation from solely narrative explanation. There appeared a search for the causes of the events and their whys and hows.