Thalassaemia is a common and debilitating autosomal recessive disorder affecting many populations in South Asia. To date, efforts to create a regional profile of β-thalassaemia mutations have largely concentrated on the populations of India. The present study updates and expands an earlier profile of β-thalassaemia mutations in India, and incorporates comparable data from Pakistan and Sri Lanka. Despite limited data availability, clear patterns of historical and cultural population movements were observed relating to major β-thalassaemia mutations. The current regional mutation profiles of β-thalassaemia have been influenced by historical migrations into and from the Indian sub-continent, by the development and effects of Hindu, Buddhist, Muslim and Sikh religious traditions, and by the major mid-twentieth century population translocations that followed the Partition of India in 1947. Given the resultant genetic complexity revealed by the populations of India, Pakistan and Sri Lanka, to ensure optimum diagnostic efficiency and the delivery of appropriate care, it is important that screening and counselling programmes for β-thalassaemia mutations recognise the underlying patterns of population sub-division throughout the region.