[Extract …] That over half of humanity now lives in towns and cities is the most complex socio-economic phenomenon of the twenty-first century. In slightly over two decades, from 2010 to 2030, another 1.5 billion people will be added to the population of cities; by 2030 that fraction will be increased to 60 per cent. Although urbanization has occurred since ancient times in human history, the most important ways in which the urbanization processes today are different from urban transformations of the past include the scale, the rate, and the shifting geography of urbanization (Seto et al. 2013: 4). Urban growth in the coming decades will take place primarily in Asia (China and India in particular) and Africa (especially Nigeria). The developing world has already entered into the high-growth, rapid transition phase of the urbanization process, marked by numerous problems and challenges including the swelling of slums and squatter settlements; lack of citywide infrastructures for services such as housing, health and sanitation; privatization and commercialization of infrastructures; city development plans based on the logic of foreign capital; the widening gap between the rich and the poor; and the changing nature of the rural–urban divide.

Scholars argue that one of the crucial aspects of the contemporary urbanization process in the developing world is the emergence of what is defined as the ‘periurban’ or semi-urban interface, where rural and urban features tend to coexist increasingly within cities and beyond their limits (Allen et al. 1999; Allen 2003, 2009; Shaw 2005). Various recommendations are being made to incorporate this new concept into both theory and practice (planning). These include the application of the urban–rural gradient paradigm as a powerful organizing tool for studying urban ecology and initiatives to come up with a specific approach to be applied in environmental planning and management (EPM) of these areas (Allen 2003: 147).

The peri-urban constitutes an ‘uneasy’ phenomenon, usually characterized by either the loss of ‘rural’ aspects (loss of fertile soil, agricultural land, natural landscape and so on) or the lack of ‘urban’ attributes (low density, lack of accessibility, lack of services and infrastructure, and so on) (Allen 2003: 136) and recent urban expansion or sprawl in the developing countries. Interestingly enough, if we look into the pages of history, we find that the sharp disconnect between the urban and the rural is only a recent occurrence, first appearing as late as the early twentieth century. Densely packed housing and central institutions within the defensive walls of the city, and residential settlement spreading far beyond that limit (a phenomenon that we might today call sprawl), was a pattern found frequently in the Near East, Asia and medieval Europe (Boone and Modarres 2006; Elmqvist et al. 2013). The layout of other ancient cities (like those of the Khmer of early medieval Cambodia, the classic Maya of Central America, and some pre-colonial African societies) was marked by a different type of sprawl or area spread, where residences were interspersed among agricultural plots in an extensive low-density continuum surrounding central institutional buildings and monuments (Evans et al. 2007; Scarborough et al. 2012; Simon 2008; Elmqvist et al. 2013). Ecosystem services, mainly in the form of agriculture, within these greater cities or broadly defined urban boundaries provided a major share of the city’s subsistence.