One of the most important trade routes ever was called the Silk Road. It was an ancient network of roads and trading posts that linked Asia and areas along the Mediterranean Sea.

As traders traveled on the Silk Road, they passed through the country we today know as Afghanistan. Today, the region continues to be a crossroads for concepts of ancient and modern, East and West, geography and history.

Afghanistan is a land of rugged mountains. Yet, this threatening landscape actually helped ancient traders, says Dr. Fredrik Hiebert. He's a National Geographic Society archaeology expert.

All those mountains mean there are valleys. These are like natural trails, Hiebert notes. "You don't really have to know too much about navigation" to know how to get through the mountains, he said. You just follow the valleys and rivers.

Graveyard Of Empires

Afghanistan sits almost right in the middle between the China Sea and Mediterranean Sea. It connected the empires of Asia, eastern Africa and southern Europe. Traders and travelers on the Silk Road could interact with the cultures of China, India, Persia, Arabia, eastern and North Africa and the eastern Mediterranean.

With Afghanistan's central location on the Silk Road, it grew wealthy.

"They not only had a lot of agriculture, they had a lot of animal wealth, because the region is really great for herding," Hiebert says. "And they had mineral wealth."

The settlements Tepe Fullol, Ai Khanoum and Bagram were popular stops in Afghanistan for traders. Today Bagram is the site of the U.S. military's Bagram Airfield.

It wasn't only goods, however, that moved across Afghanistan. Ideas about art, religion and government all mixed on the Silk Road.

The religion Buddhism, for instance, started in India. It spread to Afghanistan. Then it moved on to China, Hiebert says.

Bamiyan, in central Afghanistan, was a Buddhist center with towering statues of the Buddha on high cliffs. They were 60 to 90 meters (200 to 300 feet) tall. These were easy for traders to see, Hiebert notes.

The statues were destroyed by the Taliban in 2001. The Taliban is a violent extremist group currently fighting the government for control of the country.

Art, too, developed mixed influences. Greek architectural style, for example, is found in the ruins of Ai Khanoum, an archaeological site in modern Afghanistan's northeast. Ai Khanoum was conquered by Alexander the Great. Messages to Greek gods have been found on artifacts there.

The same wealth that made Afghanistan so attractive to ancient traders also made it a target for takeover by outsiders.

Still, Afghanistan has proved to be nearly impossible to permanently conquer. Everyone from Alexander the Great to the 1800s British Empire could not take it over. The region's climate and landscape have earned it the bitter nickname "Graveyard of Empires."

Afghanistan is straight in the center of Asia, Hiebert notes. Its weather is not affected by ocean currents. This means it is "really cold in the winter, and really hot in the summer. It's a pretty tough place to be," says Hiebert.

Historically, the region's climate and landscape have also made it difficult for Afghans to unify.

Mountains block off groups from one another. When groups meet in the valleys, there is sometimes fighting, Hiebert says.

New Silk Road

Civil and foreign wars have happened in modern Afghanistan for more than 30 years. Still, Hiebert notes, Afghanistan has still survived for 5,000 years.

Afghanistan has the resources to thrive once the country gets stable, Hiebert says. He points out that a lot of copper was just found underground there.

The country even has other natural resources that may contribute to a new Silk Road.

"We like to think that the 21st century is the century where those old networks are going to be re-established," Hiebert says. "It's not silk anymore. It's oil and gas."

Still, the archaeologist says, it may take Afghanistan years to recover from its long-running war and chaos.

"Afghanistan is a tough place, but you know what? Europe was tough after World War II," Hiebert says. After four years of war in Europe, he says, "it took a long time to repair and recover. How long do you think it will take Afghanistan, that has had over 30 years of civil war? It is not going to happen overnight."