Inclusive education is a fundamental right of all students. Despite international policy initiatives, educational exclusion is pervasive, especially in the Global South, and disproportionately affects disabled students. Barriers to inclusive education have been itemised in the literature, but in this conceptual paper that offers a novel perspective on the topic, we argue for a complexity approach to understand its evolution. Using a qualitative deductive content analysis of South African laws, policies, reports and scholarly literature, we explore three path dependencies from colonial/apartheid times that lock the country into historical patterns of categorisation and segregated schooling. These operate alongside the emergence of new and inclusive practices by actors at a system-wide and local level, made possible by inputs into the policy ecology. South Africa represents a complex, contradictory educational environment that confounds the expectation of linear progression towards greater inclusivity. Instead of identifying barriers to inclusive education, we argue for a nuanced understanding of the imbrications of historical investments and drivers of inequality, with policy possibilities and the impetus for transformation among system actors.