It is also deeply engaged with the nearby, established city. Its political institutions, business relationships, social networks and transactions are all footholds intended to give new village arrivals a purchase, however fragile, on the larger society.
The arrival city gives them a place to push themselves and their children further into the centre, into acceptability and connectedness.
The ex-villager enclave located on the periphery of our vision and beyond the tourist maps has become the setting of the world's next chapter – driven by exertion and promise, battered by violence and death, strangled by neglect and misunderstanding.
History is being written, though largely ignored, in places such as Liu Gong Li, on the edge of Chongqing, China; Clichy-sous-Bois, on the outskirts of Paris; Dharavi, the almost million-strong arrival city in Mumbai; or the Latino arrival city of Compton on the edge of Los Angeles.
Arrival cities are known by many names. They are the favelas, bustees, bidonvilles, ashwaiyyat, shantytowns, kampongs, gecekondulars and barrios of the developing world. But they are also the immigrant areas, ethnic districts, slums, banlieues difficiles, Plattenbau developments, Chinatowns, Little Indias and Hispanic quarters of wealthier countries.
The modern arrival city is the product of the most recent, and perhaps final, great human migration. The world's population has been on the move from village to city since shortly after the Second World War, when old empires crumbled and South American and Middle Eastern villagers left their homes to build new enclaves on the urban outskirts.
The transfer is entering its most intense phase now, with 200 million Chinese peasants “floating” between village and city, vast shifts under way in India and Bangladesh, and huge numbers of Africans and Southeast Asians joining the exodus. In 1950, 309 million people in the developing world lived in cities; by 2030, 3.9 billion will.
At the moment, only 41 per cent of Asians and 38 per cent of Africans live in cities – leaving a population of villagers mainly farming for their own survival. They are on the land not because it is a better life, but because they are trapped.
This is changing fast. Between 2007 and 2050, the world's cities will have absorbed an additional 3.1 billion people. The population of the world's countryside will stop growing around 2019, and by 2050 it will have fallen by 600 million.
Between 2000 and 2030, the urban populations of Asia and Africa will have doubled, adding as many city-dwellers in one generation as these continents accumulated during their entire histories.
By the end of 2025, 60 per cent of the world will live in cities; by 2050, more than 70 per cent; and by century's end, even the poor nations of sub-Saharan Africa will be at least three-quarters urban.
URBANIZATION: ALMOST A MIRACLE CURE
And that's good news. There is no romance in rural life. Rural living is the largest single killer today – the greatest source of malnutrition, infant mortality and reduced lifespans.
According to the World Food Program, three-quarters of the world's billion people living in hunger are subsistence farmers. Urban incomes everywhere are higher, often by large multiples; access to education, health, water and sanitation as well as communications and culture are always better in the city. The move to cities also reduces ecological damage and carbon emissions, by decreasing distances and increasing shared technologies.
The dramatic declines in the number of very poor people in the world around the turn of this century – with the world poverty rate falling from 34 per cent in 1999 to 25 per cent in 2009 – were caused entirely by urbanization.
It doesn't just improve the lives of those who move to the city; it improves conditions in the countryside too, as emigrants send villages back the money they need to turn agriculture into a business with salaried jobs and stable incomes.