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Huge Ancient Civilization’s Collapse Explained

The fall of the greatest mystery of civilization's earliest cities around the world 4,000 years ago in what is now India, Pakistan, Nepal and Bangladesh which now seemed to have the main cause - the ancient climate change, researchers say.

Ancient Egypt and Mesopotamia, perhaps best known as the first great urban culture, but the biggest is the Indus or Harappan civilization. Culture that once extended over 386 000 square miles (1 million square kilometers) in the plains of the Indus River from the Arabian Sea to the Ganges, and the peak can be accounted for 10 percent of the world's population. Civilization was built nearly 5200 years ago, and slowly destroyed between 3900 and 3000 years ago - most of the population left the city, migration to the east.

"I know first about Egypt and Mesopotamia, the Indus civilization, however, the larger of the two, was virtually forgotten until 1920," said Liviu Giosan researcher, a geologist at the Woods Hole Oceanographic Institution in Massachusetts. "There are many ways still a lot we do not know about it."

Nearly a century ago, researchers began to discover the remains of many Harappan settlements along the River Indus and its tributaries, as well as a vast desert region on the border of India and Pakistan. Evidence is found for the sophisticated cities, links to the sea in Mesopotamia, the internal routes of trade, arts and crafts, and yet undeciphered writing.

"They have ordered the city grid, with a tremendous pipeline, which is not found again until the Romans," said Giosan on LiveScience. "It seems they have become more democratic societies in Mesopotamia and Egypt -. There are major structures have been developed for such an important personalitiess kings or pharaohs "

Like their contemporaries in Egypt and Mesopotamia, Harappans, named after one of their largest city, living alongside the river.

"Until now, speculations abound about the mysterious connection between ancient cultures and life-giving river is strong," said Giosan.

Now Giosan and his colleagues reconstructed the landscape of the plains and the river where it had been forgotten civilizationdeveloped. Present their findings explain the mysterious fate of this culture.

"Our study provides one of the clearest examples of climate change that caused the collapse of a whole civilization," said Giosan.

The researchers first evaluated by the satellite data from the landscape and affect the nearby river Indus. From 2003 to 2008, the researchers then collected sediment samples from the Arabian Sea coast in the rich valley for irrigation northern Punjab and the Thar Desert to determine the origin and age of sediments and develop the landscape changes.

"It's hard work in the desert - temperatures over 110 degrees Fahrenheit during the day (43 degrees C)," Giosan mind.

After collecting data about the geological history, "we can re-examine what we know about the settlement, what people plant crops and when, and how both the agricultural and settlement patterns have changed," the researchers said Dorian Fuller, an archaeologist at University College of London. "It brings new insight into the process of population shift to the east, turn into many small farming communities, and the rejection of last during the Harappan times."

Some argue that the center of Harappa receive water from the glacier-fed rivers of the Himalayas, thought by some to Sarasvati, the sacred river of Hindu mythology. However, the researchers found that only rain-fed river flowing through the region.

Previous research suggests that the Ghaggar, an intermittent stream that flows only in the rainy season strong, can approach the location of the Sarasvati. Archaeological evidence suggests the river, which disappears in the desert all the way dry Hakra valley, is home to the completion of an intensive period of Harappa.

"We thought we settled a long debate about the mythical Sarasvati River," said Giosan.

First, the rain-drenched river researchers identify vulnerable to floods. Over time, the monsoon is weak, allowing agriculture and civilization developed along the river flood-fed for nearly 2,000 years.

"The illumination by the sun - solar energy received by Earth from the sun - are inconsistencies in the cycles, which can affect the rainy season," said Giosan. "In the last 10,000 years, the Northern Hemisphere is the highest insolation of 7,000 to 5,000 years ago, and since there is reduced insolation. All of the climate on Earth is driven by the sun, so the wind is less influenced by insolation, decreased strength. means more rain captured in continental regions affected by monsoons from time to time. "

Finally, the monsoon-based river held very little water and dried, making them opposed to civilization.

"The Harappans is actively utilizing the window of opportunity - a sort of" Goldilocks civilization, "said Giosan.

Finally, throughout the centuries, Harappans apparently escaping along the route to flee to the east towards the valley of the Ganges, where the rainy season can still be relied upon.

"We can see that the shift involved a change to the east of more local forms of economic - small, local communities are supported by rainfed agriculture and reduced the flow," says Fuller. "It can make a small surplus, and large cities are supported, but not reliable."

This change has spelled disaster for the city of the Indus, which is built on a huge surplus that looks over the weather, before more wet. Distribution of the population in the east is not intended to support the workforce concentrated urbanism.

"The city collapsed, but the small farming communities and developing sustainable," says Fuller. "A lot of urban art, such as writing, faded, but agriculture continues and really varied."

The findings could help guide the archaeological exploration of the future of the Indus civilization. The researchers are now able to better predict the settlement could not be more significant, based on their relationship to the river, said Giosan.

It remains unclear how the monsoon is a reaction to modern climate change. "If we flood caused the greatest humanitarian disaster in Pakistan's history as a sign of increased activity of the rainy season, but it does not bode well for the region," said Giosan. "This area has the largest irrigation schemes in the world, and all the dams and channels will become obsolete in the face of the summer flood season, the increase will bring."

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