But new threats have emerged to centuries-old sites from illegal excavations by amateur archaeologists and criminal gangs who compete to unearth relics worth millions of dollars abroad.

“This is our history because we were also Buddhist at that time. This is cultural heritage and the future of a nation is based on cultural legacy,” said Abdul Azeem, deputy director of Pakistan's Archaeological Department in Islamabad.

Remnants of Buddhist art and culture can be found at dozens of sites in north-western Pakistan which, in marked contrast to its tolerant past, is in the clutches of radical Islamic fundamentalism.

Islamists are hostile the pre-Islamic heritage and want to erase it. In Afghanistan, they destroyed two giant Buddha carvings in 2001.

The act was repeated in Pakistan in 2007, when militants blew up the face of a 1,500-year-old rock carving of Buddha in the Jahanabad area of Swat, bringing condemnation at home and from abroad.

“The destruction of Buddha was a great loss to our heritage by Taliban, who also later sent suicide bombers to attack Swat Museum during the military operation of 2009,” Azeem said.

The attack forced the authorities to move the rare archaeological treasures from Swat to Islamabad. They were returned this year to Khyber-Pakhtunkhwa province to be put back in the museum.

The vandalism also hit the region's once booming tourist industry. The 6-metre tall Buddha image was one of the main attractions for local and foreign visitors from China, South Korea and Thailand before the rebels took control of the area in 2007.

Apart from the systematic destruction of monuments, the Taliban also stopped digging at sites in Swat to keep the non-Islamic past buried.

An army offensive in 2009 cleared out militants, and steps were taken to rehabilitate the damaged sites and the Jahanabad carving is being restored by an Italian team of archaeologists. But nothing was done to check the illegal excavations that restarted.

“I think the illegal digging of the historical structures has increased after the fall of the Taliban. They banned it and strictly punished those involved in it,” said Nasir Khan, a senior official at Taxila Museum, one of the main repositories of Gandhara-period items.

Official apathy, corruption and the mountainous terrain make it easy for small, clandestine digs.

Azeem says post-Taliban local administrations do not share the militants' hatred for the pre-Islamic historical sites.

“The elements of corruption cannot be ruled out but there is no official complicity in the illegal excavations,” he said. “Officials know that it is against law and they take action against people involved in it.”

It is believed that local residents and expert outside looters are involved in unauthorised excavations. Stolen artifacts are sold to various dealers who send them to the southern port of Karachi.

International dealers involved with smugglers then ship the rare relics to Europe or the United Arab Emirates.

Police in Karachi intercepted a truck on July 8, recovered more than 300 iterms and arrested two people.

Agents then raided a building in the city's Korangi district and seized a quantity of small artifacts and two crates containing giant sculptures that each weighed more than 5 tons.

Qasim Ali Qasim, director of Sindh province's archaeology department, said they belonged to the Gandhara era but their exact age would be determined after analysis.

“The recovered articles are truly priceless, but for the sake of an estimate we can say that their value is more than 10 million dollars,” he said.

Shabir said initial police investigation showed links with people living in Islamabad and nearby areas of lawless Khyber-Pakhtunkhwa province, where the majority of Gandhara-period sites, including the ruins of Swat, are located.

Improved security since the militants were driven out has increased the number of people coming to see the pine-clad valleys and snow-covered mountains of Swat.

The ouster of the Taliban may have saved the objects from religious vandalism, but it has also led to a rise in fortune seekers coming to find the rare objects.

“Now everyone can go there unchecked,” said Nasir Khan of Taxila Museum.