Abdul Qadir Timori describes the moment he discovered a rare, perfectly preserved, 1,500-year-old wooden statue of a Buddha in the ruins of an ancient monastic city in eastern Afghanistan as one of the most joyous of his life.

As director of archaeology at Afghanistan's Ministry of Information and Culture, Timori was leading the excavation of a Buddhist temple on an arid mountainside not far from Kabul.

"On all four sides of the temple, there were Buddha statues that would have stood at four to five metres. Unfortunately, only the legs remained; the upper-body and head parts had been destroyed due to the passage of time," he says. "We also found a reclining Buddha there.

"I went to work cleaning the spaces between the legs of all these statues when my hand suddenly touched wood. As I turned this wooden object and started cleaning it … I was so overjoyed that I nearly stumbled off the hill. I shouted to my colleagues nearby and beckoned them to come and see the most exquisite find - the first wooden Buddha ever found in Afghanistan."

What Timori found that day in mid-2010 is, in fact, the only known example of a wooden seated Buddha from antiquity to have survived intact anywhere. It dates back to some time between the 5th and 7th centuries, when its resting place was a wealthy and powerful hub of Silk Road trade and manufacturing established and run by Buddhist monks who had come to this barren mountainside to dig for copper.

The carving is of a robed Buddha sitting cross-legged on a lotus throne in meditative prayer, right hand in the gyan mudra position with the palm facing out. Solid, heavy and in almost immaculate condition, it measures 20cm from the tip of the halo around the curly haired head to its ornately carved base.

"Similar wooden statues may have been found in places like India and Sri Lanka but we believe that the Mes Aynak Buddha is perhaps the oldest of its kind that's so far been found anywhere," Timori says. "The reason it's in such good shape and intact, in my view, is because it rested in the small space between the legs of two larger, clay Buddhas without much pressure on it during all that time."

Timori's Buddha, now on display at the National Museum of Afghanistan, in Kabul, is among more than 1,000 artefacts that have been excavated from Mes Aynak, a site that covers 1,000 hectares at the foot of Baba Wali Mountain, 40 kilometres southeast of Kabul, in the heat and dust of Logar province. It is one of the world's richest stores of treasure and knowledge dating back at least 2,000 years. Given that the deeper layers in the mountain have yet to be touched by the delicate brushes of patient archaeologists, it could date back even further.

Experts say the relics that have been uncovered here since excavation began in earnest, in 2009, are recasting the history not only of Afghanistan but also of Buddhism and its spread from India across the subcontinent to China, Korea and Japan. Mes Aynak is also yielding information on the influence that Buddhism had, beyond philosophy and religion, on the economic and political development of successive empires that stretched across this vast expanse.

"What is most interesting for us is that, until now, Buddhist monasteries, monks and Buddhism have not been seen as an economic force," says Philippe Marquis, head of the Kabul-based French Archaeological Delegation in Afghanistan (Dafa), who has worked at Mes Aynak, alongside Timori, for four years. "The economic issues of Buddhism have never really been understood or properly studied.

But here we have the possibility to understand that if Buddhism had such a development in this area, it was because it also integrated economic factors, and social and political factors - and that is a very interesting thing."

Mes Aynak was first explored in 1963; its potential importance to the study of Afghanistan's Buddhist history was recognised in the mid- 1970s; and a few years later, Soviet geologists did some minor excavation work, uncovering some ruins. In 1980, Dafa archaeologists collected pot shards and the area was mentioned briefly in an academic publication in 1982.

Archaeologists' endeavours were to be sidelined by more than two decades of strife in Afghanistan, however. The Soviet Union sent troops into the country in December 1979, to prop up what was then a communist government. That action led to a bitter war, which segued into a civil war, followed by a horrific period of rule by the fanatically conservative Islamist Taliban.

During the Taliban years, from 1996 to 2001, Mes Aynak was an al-Qaeda training camp, which Osama bin Laden used in preparation for the September 11 attacks on the United States.

Very little archaeological work could be done here throughout the decades of war; and Afghan archaeologists who were able to make a rare visit in 2004 found that the site had been extensively and disastrously looted not long before.

The Taliban was thrown out by the US-led invasion in 2001; but conflict continues to this day in the form of a Taliban-led insurgency. International combat troops are due to withdraw by the end of next year, leaving the Afghans largely to control their own fortunes.

One useful legacy of the Soviet occupation, however bitter memories of it may be, is extensive knowledge of Afghanistan's mineral resources, which the current government has begun exploiting in order to bring in hard currency that will fund post-war development. The Soviet surveys - often cited by the Afghan authorities, the US and its Nato partners as the troop departure date nears - found that Afghanistan sits on US$1 trillion worth of minerals, including copper, iron ore, gold, silver and a range of minor metals and rare earths, as well as gems. With an estimated US$2 trillion worth of hydrocarbons, the country is also a future source of oil and gas.

Mes Aynak is the site of one of the biggest copper deposits in the world, with about 5.5 million tonnes of high-grade ore.

"The monks first came to Mes Aynak for the copper," says Andy Miller, a British heritage consultant who has worked extensively in Afghanistan, most recently with the Aga Khan Trust for Culture. "They used the copper to create goods that were traded up and down the Silk Road trading routes between India and the Far East for hundreds of years. That wealth in turn fuelled the growth of Mes Aynak into what appears to have been one of the most important points, economically and politically, on that web that criss-crossed the region and on into the West."

In 2007, the Afghan government signed a contract with a Chinese state-owned mining consortium, China Metallurgical Group (MCC), worth US$3 billion for 30 years of exploration and exploitation. In the course of negotiations, the Afghan government commissioned an archaeological assessment of the area, and then came to an agreement with MCC that mining would not commence until the archaeologists were satisfied with the extent of their excavation work.

Against this backdrop has been running a low-key and largely ill-informed campaign to ban all mining at the site. Its protagonists, who include American documentary filmmaker Brent Huffman, want Mes Aynak preserved in its entirety. Huffman, who has accused the Ministry of Mines of corruption, wrote recently on CNN's website: "My fear is that in the future Afghanistan will consist of hundreds of these gaping toxic craters, and the resources the country needs for its own development will be lost. Afghans will see no benefit. They will suffer from irreversible environmental devastation and the permanent loss of invaluable cultural heritage."

Experts such as Marquis and Timori, however, say looting and the effects of the harsh local environment would destroy the exposed site within years, and that preserving its treasures is the only option. By excavating what they can, they believe they are ensuring Mes Aynak plays a dual role in Afghanistan's future - cultural and economic.

"Mes Aynak is indeed important to the country as both a source of valuable minerals and of Afghanistan's ancient history. It has been agreed that mine extractions should not harm the artefacts," says Omar Khan Massoudi, director of the National Museum.

For Marquis, the two are inextricable - without the mine there would be no artefacts to excavate.

"What everyone has to understand and take responsibility for is that if we don't document these sites they will disappear for good. That's why we are in a tight race. If no one takes any notice, then due to looters, due to development, due to natural factors - things that are out of our control - the cultural heritage of this country will simply disappear," he says.

Afghanistan's minister for mines, Wahidullah Shahrani, tells Post Magazine that the archaeologists have been given until the end of next month to complete their work.

"Once I get clearance from Dafa and from our Ministry of [Information and] Culture, then we will issue the licence to MCC to begin mining," he says.

Experts including Marquis - but also mining industry professionals - do not believe, however, that any mining work will begin here before 2016. With the troop exodus, a presidential election next year and parliamentary elections in 2015, it will be some time before Afghanistan can present a stable enough political or security environment for such large-scale work.

This area of Logar still ripples with insurgency activity, as MCC employees found when they came under regular gunfire and rocket attacks while constructing buildings at Mes Aynak. They were pulled out last year, with no date set for their return or the resumption of work.

Marquis says he is in no hurry, having been told, when excavation at Mes Aynak began in April 2009, that it had to be completed in 12 months. Four years on, he says, the archaeological teams employ up to 650 people from local villages who "have learned this is something that is very important for the country. Now they say they would like to have a museum in Logar, a place where it should be possible to show to their children what has been found in this place, in Mes Aynak."

The objects that have been excavated so far are stored under tight security in a hangar built near the site by the US government and military. Massoudi says pieces that are too delicate to move may be displayed locally. There are plans to build a US$10 million wing of the National Museum in which to display the Mes Aynak treasures.

Dafa's Nicolas Engel has identified Mes Aynak as being "from the late Kushan period up to the late Shahi period", or the second to the ninth centuries AD. This was at the peak of the kingdom of Gandhara, which flourished from the first millennium BC to the 11th century and covered what is now northern Pakistan and eastern Afghanistan.

Among the breathtaking trove is a huge collection of Buddha and bodhisattva statues, or parts of statues; most standing, at least one reclining, and of heights varying from 15cm to five metres. Of some, only the calves and feet remain, with draped robes covering the knees, and the scale indicating their towering original height. They are made from a range of materials - stone, unbaked clay, plaster and wood. Some of them are ornately decorated with red, white, black and blue pigments; often the heads are gilded. Coins of high quality, painted and stamped ceramics, wall paintings and texts have also been found.

One object that has particularly impressed archaeologists is a small relief of a "pensive bodhisattva" found in the same monastery as Timori's seated Buddha. The stone carving measures 5.3cm high and has been dated to the fourth century. It shows "a young prince clad in a dhoti, wearing necklaces, earrings and a bracelet, sitting under a pipal tree", according to one description. The prince is sitting on a round stool; a monk stands on his right.

There were at least a dozen monasteries here, along with huge public buildings entered through massive doorways that led into cavernous vestibules lined with statues and adorned with colourful friezes. There appear to have been hundreds of stupas; some of the remains bear traces of the plaster that once covered and coloured them; some have remnants of staircases; others have supporting pillars.

There are also what were probably residential buildings for administrative staff and those who worked in the copper mine, smelters and workshops.

With only the surface scratched, what is already clear is that Mes Aynak was a thriving city built on a copper mine first identified by monks who saw its potential at a time when trade via the vast network of the Silk Road was opening up the world and expanding horizons, connecting East with West, creating wealth and spreading knowledge. Perhaps, in a way, the developments were comparable to the inventive dynamism of the late 20th century.

The painstaking work at Mes Aynak has confirmed the dominance of Buddhism in Afghanistan for a millennium - from around the first century BC, to the 10th or 11th century. The last human occupation of the buildings here has been dated to the 13th century; Buddhist chapels appear to have fallen out of use by then, and ceramic shards from the period indicate Islam had taken over. There were certainly Muslim settlements in the area at that time.

In the centuries since Buddhism's decline, Islam's rise and Afghanistan's slide into the ranks of the world's poorest countries, Mes Aynak has been overrun by looters who have left behind little of what must have been a startling bounty.

Still, much of what survived and has been unearthed at Mes Aynak predates the giant Buddhas of Bamiyan, which were condemned as idolatrous and destroyed by the Taliban in 2001. Those towering masterpieces were carved into the side of a mountain in the sixth century.

It may be that the leftovers of a once-thriving civilisation will shine a light on a period that provides an example of what Afghanistan has been before and may be again - peaceful, prosperous, powerful and proud.

"These monasteries were the first place where monks were propagating Buddhism as a philosophy," says Marquis. "But it was also an excellent opportunity to have trading posts scattered all over the Silk Road, a huge trading area.

"What we are starting to understand is that each time Afghanistan was the centre of an important political power it was very often related to their capacity to exploit the natural resources," he says. "It could be copper, it could be iron, it had been silver, it had been gold. So archaeology is a very good way to document a process which is more or less at work right now - and which could be a very good example to [use in giving] back to Afghanistan real power."