From the mid-19th to the early 20th centuries, the forces unleashed by the age of European imperialism and its rapid encroachment on dār al-Islām increasingly brought the hajj under the scrutiny and regulation of non-Muslim powers. The driving force behind these dramatic changes in administration of the hajj was the expansion of the British Empire. As Britain's power in the Indian subcontinent grew, so too did its maritime supremacy throughout the Indian Ocean basin. Looking to secure its access to India, ward off its European competitors, and expand its commercial interests in southwestern Arabia, the Red Sea, and the Gulf of Aden, Britain's role in the region was intensified by the transit opportunities that emerged with the development of regular steamship routes between the Mediterranean and India from the 1830s to the 1860s and the eventual opening of the Suez Canal in 1869. With the exponential growth of maritime traffic that accompanied these technological advances came a similarly dramatic rise in the oceangoing pilgrim traffic from and through British India. Owing to this expansion in the number of seaborne pilgrims, the hajj soon came to be recognized as the primary conduit for the globalization of epidemic diseases, such as cholera and plague.