Who is a ‘neighbour’? Bulmer's words capture the most intuitive definition. They are ‘quite simply people who live near one another’ (Bulmer, 1986: 18). Indeed, geographical proximity is an essential characteristic of being a neighbour. Greater proximity leads to greater opportunity for contact between individuals. It follows then that people may choose to initiate contact and sustain it, depending on whether they find the outcome of engagement beneficial. The point is, proximity makes contact inevitable. As Cheshire (2015) says, even when it is someone whom you do not wish to actively interact with, physical proximity by itself makes it difficult to ignore them entirely.

Most studies favour contact between ethnic groups and find strong evidence supporting diversity in neighbourhoods. Mixing is desirable for it can not only encourage beneficial alliances across group boundaries but also reduce existing prejudice between groups (for example, Allport, 1954; also Piekut and Valentine, 2017; Pettigrew, 1998; Schmid et al., 2008), and may even deter future violence (Jha, 2014; Varshney, 2002). Spatial scale is crucial here. Parts of the world where different religions, races, and nationalities are in frequent contact are also prone to high levels of conflict, even violence.