This introduction presents an overview of the key concepts discussed in the subsequent chapters of this book. The book introduces the reader to new and emerging research in the broad field of 'imperial migration'. It shows how this 'new' migration scholarship is helping to develop and deepen our understanding of the British World. The book focuses on the Reverend Thomas Malthus, arguably the most important Victorian thinker on emigration, and his ideas about how population movements presaged forces within sectors of a pre-industrial economy. It investigates the varieties of engagement with Indian Christians and non-Christians between 1860 and 1940. The book discusses the dynamics of inter-faith dialogues between Christians, Hindus and Muslims and the cultural transfers which occurred at all levels of Welsh missionary activity both in the field and at home.