This study, employing the biological metaphor of the “colony,” examines the structure of collective mentality in Islamic history and its role in the blockage of rationality and the stagnation of political thought. The concept of “intellectual colonization” here refers to a process through which religious and political institutions, by relying on the official interpretation of sacred texts and the systematic control of knowledge production and distribution, have shaped homogeneous and static mental patterns within Muslim societies. From the early Islamic period and the Umayyad and Abbasid caliphates to the Safavid and Ottoman states, this process functioned as an effective instrument for consolidating political legitimacy while, at the same time, constricting the sphere for dissent, philosophical inquiry, and rational sciences. Historical cases—such as the burning of Avicenna’s philosophical works, the prohibition of trading in philosophical books, and the suppression of thinkers like Suhrawardi—demonstrate that such policies were not occasional but structural, persisting over the centuries. Adopting a descriptive-analytical approach with critical review, the article shows that the obstruction of rationality was not merely the consequence of despotic political will but, owing to the institutionalization of uniform mental frameworks within the collective mentality of Muslims, endured even under changes of regime. The author concludes that overcoming this historical deadlock requires rethinking the mechanisms of mentality formation, breaking free from epistemological monopoly, and reviving the authentic rational-critical tradition that can restore the civilizational potential of the Islamic world.