Central Asia. These cities were high density in form and enclosed by walls. They
were constructed from masonry, and the houses were usually multistoried. Until
1000 BCE, the populations of some of the cities in this region continued to increase,
with livelihoods based on cultivating wheat as their main crop. Some cities in this
region endured for long periods; for example, Jerusalem and Aleppo have existed for
more than 3000 years.
In contrast to the mid-latitude arid region, there was abundant water and flora in
monsoon Asia, which includes South, Southeast, and East Asia. Monsoon Asia
covered an area ranging from the temperate to the tropical zones. The people in
this region used wood and leaves to construct their homes instead of the masonry of
the arid zone. They lived amid greenery and farmed vast rice fields. Consequently,
they tended to create flat, sparsely populated cities.
Whether the urban morphology was organically shaped or geometrically planned
was determined by more than just the geographic region. It was also a matter of
authority and governance. For example, the city of Angkor Wat in the twelfth
century had orthogonal grid plans, but the vast cities of Edo and Ayutthaya, built
in the seventeenth century, had irregular layouts and moats rather than the city walls
of the mid-latitude arid region.
It is difficult to determine the border between the mid-latitude arid region and
monsoon Asia, especially in South Asia and China. It is presumed that the Indus
Valley and Huang He civilizations belonged to the former, whereas the Ganges and
Chang Jiang civilizations belonged to the latter. In the mid-latitude arid region,
wheat and barley were the staple crops, whereas in monsoon Asia, the main crop was
rice. There were many early cities in both the mid-latitude arid region and
monsoon Asia.
A third region, upper Eurasia, encompassed the cool temperate and frigid zones
from upper Europe to the Siberian plateau. The cities here were influenced by those
of the mid-latitude arid region. Under the Roman Empire, many colonial cities were
founded in this region between the first and fourth centuries. Then, in the medieval
era, many small, walled cities arose. The urban forms differed between these periods;
the cities built in the former period were geometrical grid cities, whereas those built
in the medieval period were organic cities, like the Islamic cities discussed earlier.
The Latin America region, from Mexico to the South American continent, had an
urban history before 1500 as demonstrated by cities such as Tenochtitlan. After the
sixteenth century, the Spanish and Portuguese aggressively colonized these “new”
continents, with the Spanish establishing grid cities, with squares and churches, and
the Portuguese constructing fortified forts as colonial cities.
The appearance of cities was delayed elsewhere, in North America, Oceania, and
from the middle to the south of the African continent. There were different urban
traditions in each of these continents prior to their colonization by the European
countries. After the Industrial Revolution in the nineteenth century, Western Europe
had a strong influence over North America and Oceania. Thus, it is useful to connect
these two areas because of their relation to upper Eurasia region. Hence, we create
two further regions: first, North America and Oceania, and second, the sub-Saharan
Africa region, which covers temperate to tropical climate zones.
5 Regional Diversity and Sustainability of Megacities in Global Historical. . .
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