<P> In the United States and Canada, suburb can refer either to an outlying residential area of a city or town or to a separate municipality or unincorporated area outside a town or city . </P> <P> The earliest appearance of suburbs coincided with the spread of the first urban settlements . Large walled towns tended to be the focus around which smaller villages grew up in a symbiotic relationship with the market town . The word' suburbani' was first used by the Roman statesman Cicero in reference to the large villas and estates built by the wealthy patricians of Rome on the city's outskirts . </P> <P> Towards the end of the Eastern Han Dynasty (up until 190 AD, when Dong Zhuo razed the city), the capital, Luoyang, was mainly occupied by the emperor and important officials; the city's people mostly lived in small cities right outside Luoyang, which were suburbs in all but name . </P> <P> As populations grew during the Early Modern Period in Europe, urban towns swelled with a steady influx of people from the countryside . In some places, nearby settlements were swallowed up as the main city expanded . The peripheral areas on the outskirts of the city were generally inhabited by the very poorest . </P>

Explain the growth of suburbs in terms of