The history of cities was once the history of empires, writ small. Imperial Rome, Baghdad under the Abbasids, Mamluk Cairo, Ottoman Istanbul, Beijing during the Ming and Qing dynasties—the megacities of the past, at their demographic peaks, reflected all the sordid glory of political and economic dominance. Nor was this any less true when London, gilded with industrial and imperial gains, became the world’s largest human concentrate soon after the Napoleonic Wars, or when New York succeeded it one fine day in the 1920s—as clear a signal as any of America’s rise.

But the connection between global power projection and urban gigantism is soon to be no more: the megacities of the near future will sprawl far beyond even China, India, and Brazil, across lower- and middle-income countries on the geopolitical margins—wherever fertility rates, migration patterns, and convenient topography will them into being. Below, a crib sheet, in no particular order, to just a few of these emerging, barely-known behemoths:

Jakarta
The metropolitan area surrounding the Indonesian capital—officially branded with the unwieldy acronym Jabodetabek—looks set to overtake Tokyo as the world’s most populous city. It’s already nearly three times as densely inhabited, although official city limits include an archipelago of over a hundred islands, many of them uninhabited, floating in the Java Sea. What expats cheekily call the Big Durian was termed by Indonesian writer Pramoedya Ananta Toer “a place for all runaways,” a creole capital opened for business by the Dutch East India Company, just as the Dutch West India Company was setting up a certain city on the Hudson River.

Dhaka
Dependent on a fleet of at least 400,000 rickshaws and one of the most densely populated cities in the world, the urban heart of Bangladesh has grown at lightning speed since becoming the newly independent nation’s capital in 1971. The city’s architectural crown jewel—the National Assembly Building complex, designed by Louis Kahn—was spared aerial bombing during the war of independence, reportedly because the pilots mistook it for an ancient monument, but the city has suffered grievously from years of martial law, natural disasters, and extreme congestion.

Kinshasa
According to The Economist, “By 2020 there will be thirty or forty or more African cities larger than Rome or Berlin.” Nevertheless, it comes as a shock to learn that the capital of the Democratic Republic of Congo—one of the planet’s poorest and most war-torn countries—will soon surpass Paris to become the largest Francophone city in the world (although the city’s principal language is Lingala). Once a collection of fishing villages on the banks of the Congo River, later the Belgian colonial outpost of Leopoldville, Kinshasa still has semi-rural villages within its boundaries—if peace and prosperity ever returned, could it become the cosmopolitan core of a new Central Africa?

Manila
“Metro Manila” encompasses sixteen cities and twelve million people (going on twenty million, and not counting urbanized areas just outside the official metro region). Founded on an isthmus by three Spanish conquistadors, the economic and political life of the city is still dominated by Spanish and Chinese elites—though the population also increasingly reflects the tremendous ethnic diversity of the Philippine archipelago.

Tehran
The birthplace of the Iranian Revolution has become a thorn in the ayatollahs’ side—the government recently announced plans either to move the capital elsewhere or build a new one “for security and administrative reasons.” Huge numbers of state-owned enterprises, several universities, and as many as five million residents could be pressured into leaving the city, if President Ahmadinejad—who cites seismic dangers from the city’s hundred-plus fault lines—has his way. Nonetheless, a city of twelve million won’t disappear overnight, especially one blessed by the snow-capped Alborz mountains and within easy reach of Caspian shores.

Ho Chi Minh City (Saigon)
Although by far the largest city in the world named for a single individual, it’s not clear that Vietnam’s economic capital, often compared to Shanghai, would give Uncle Ho much pleasure. (He became a consummate Hanoian after having lived in New York, London, Paris, Milan, Moscow, and Guangzhou, among other cities.) The city’s District 1 is a world apart, enjoying full-throttle capitalist splendor, while outlying districts steel themselves for an influx of more millions from the countryside.

Lima
Another maritime city founded by conquistadors, the Peruvian capital has a surprising amount in common with Manila, almost 11,000 miles away: tremendous wealth disparities, an old-time Hispanophone elite, and a vast hinterland of indigenous peoples who have become part of the city’s fabric. The only megacity on the west coast of South America, Lima may even come to rival in scale the wealthier, Atlantic-facing megacities of São Paolo, Rio de Janeiro, and Buenos Aires.

Karachi
Karachi seems to look as much to the fast-urbanizing Persian Gulf these days as it does to the rural mountainous hinterlands of northern Pakistan, beloved of the Taliban. Divided under the British into a “white town” (for the colonizers) and a “black town” (for everyone else), Karachi began swelling to its current, enormous proportions (over 13 million) after Partition brought an influx of Muslim refugees, and the city shows no signs of no stopping, even though the politicians decamped long ago.

Khartoum
Why are many of the world’s fastest-growing cities (like Kabul and Sana’a, both growing nearly 4% per year) within conflict zones? Once an outpost of the slave trade in the Sudan, located at the confluence of the Blue Nile and the White Nile, Khartoum seems an unlikely place for five million people to call home—let alone the ten million projected to live there in a few decades.

Istanbul
Unlike the others, Istanbul has been a megacity twice before, under both Byzantine and Ottoman rule. At around thirteen million souls, the largest city in Europe is still growing, fueled by migrants from the Anatolian plateau (of the conservative, industrious Muslim stamp represented by Turkish President Abdullah Gül), but also by job-seekers from the Balkans and south-eastern Europe. Decades of population decline and cultural ebb followed the Ottoman unraveling and the flight of the city’s Greeks, Armenians, and Jews, but the gradual return of the city’s expansive cosmopolitanism and its third coming as a global megacity are a heartening sign: perhaps past and future megacities can reach some kind of understanding.