Background: This paper critically examines the bellicist theory, which posits war as central to national unification in modern state formation. While influential, its applicability to the Third World, particularly Africa, is debated. The research gap lies in explaining nation-building in the absence of war, as exemplified by Tanzania's high national identity despite lacking significant conflict, contrasting with Kenya's lower identity despite interstate war. The central question is: What drove a high national identity in Tanzania despite the absence of war? Methods: A qualitative comparative method (QCM) was employed to analyze post-colonial state formation in Tanzania and Kenya; Results: The findings suggest that post-colonial state policies—discontinuing colonial legacies, fostering inter-ethnic embeddedness, and establishing equal citizenship—are key drivers of higher national identity; Conclusions: this study challenged the necessity of war for nation-building, highlighting the importance of state-led integration processes via inclusive and equal policies to all.