The above chart of the world’s biggest cities since 4000 BC, created by Business Insider, demonstrates, among other things, that urban growth has not always been steady and sure.
Consider that at around Year 1 of the Christian era, Rome was estimated to have had a population of 1 million while Chang’an, an ancient Chinese capital today known as Xi’an, boasted about 500,000 inhabitants.
Yet, within 600 years, the largest city in the west, by now Constantinople, had but 125,000 individuals, while the biggest in the east, although still Chang’an, was down to half its former size.
Clearly, urbanization was a fluid concept, influenced by disease, warfare and trade.
Another interesting takeaway is that while Rome may have been the largest city the world had ever known around the time of Christ, if you fast-forwarded 1500 years, Constantinople, then the largest city in the west, was a staggering 90 percent smaller than Rome had been at its height.
In fact, it would be more than 1800 years after Rome’s apex before another city in the west would again reach the 1 million level.
The relatively recent impact of the agricultural and industrial revolutions, urbanization and improvements in health care can be seen in the rapid growth of cities such as London and Tokyo.
London mushroomed from 900,000 in 1800 to 6.6 million a century later, while Tokyo’s growth between 1900 and 2013 is even more staggering. The Japanese capital grew from 1.75 million in 1900 to more than 37 million today, despite massive devastation and loss of life inflicted upon the city during World War II.
Finally, consider how many of the above cities once regarded as the largest in their sphere of the world are largely unknown today.
Evidence of the transitory nature of notoriety, one supposes.
(Top: Chart of world’s biggest cities since 4000 BC. Click to embiggen. HT: Slate magazine.)