A storm is brewing in a notoriously tempestuous corner of southwest Colombia; clouds of pristine white taffeta and riotous red silk spiral like mini tornadoes as dancers perform in a public plaza beneath the threatening shadow of a furious battle memorial.

A mixture of modernist yellow pillars, muscular stallions and arrow-shooting warriors, the 1974 artwork was built in honour of Gaitana, a heroine from the indigenous Yalcon tribe who fought Spanish conquistadors in Colombia's Upper Magdalena Valley.

Extending from thriving city Neiva, the Huila region is characterised by dense forests, swollen rivers and a history of conflict. Used as a hideout by Farc guerrillas, it was deemed largely off limits in the Eighties and Nineties - a source of frustration for foreign travellers eager to discover a wealth of archaeological treasures buried within.

"That was a dark time," says Freddy, a rags to (relative) riches guide, who learned to read and write as an adult, determined to find employment in the area's growing tourism industry. Hinting official forces may have played their own part in the drawn-out, bloody episode, he adds somewhat cryptically: "It was more complex than you can imagine."

But in recent years peace has resumed and, although never to be forgotten, the threat of machete-wielding kidnappers is no more real than a symbolic, benign statue.

Ghosts of the past strangle the impenetrable jungle like winding parasitic vines, but some stories of death and warfare are more mystifying than macabre - particularly those relating to the culture of San Agustin, a pre-Columbian community who lived in a valley along the country's longest river, Magdalena.

Carved from volcanic rock 2,000 years ago, a collection of 600 statues is the only evidence of their existence. The largest group of religious monuments and megalithic sculptures in South America, it was granted UNESCO status in 1995.

Currently, the fragile artefacts are protected only by rudimentary wooden shelters and there's limited information available for visitors. But last month, the Colombian government pledged to invest almost US $20 million in 15 tourism infrastructure projects in 2018, including the San Agustin Archaeological Park.

A growing number of flights from Bogota to Pitalito, a 30-minute drive away, also cuts out the 220km schlep from the region's gateway Neiva - opening the door to one of the continent's most intriguing historical sites.

What are these strange statues?

Towering up to seven metres high, with weapons strung across their backs and dagger-sharp teeth protruding from bottom lips, the surprisingly well-preserved statues appear threatening and demonic.

Each one is unique, adorned with a different expression and symbolic design; some feature sacred animals such as eagles and frogs, and others show heightened states of meditation. Freddy tells me one vomiting figure depicts the practice of taking ayahuasca, an hallucinogenic medicine used by people in the Amazon basin.

Although various theories abound about the origin of these people, researchers unanimously agree the jungle area where they were found was used as a burial site, and it's currently considered to be the world's largest necropolis.

Who were the San Agustin people?

Very little is known about the culture, although archaeologists believe it flourished between the first and eighth centuries. Some claim the tribe may have eventually been forced out of the region when the Yalcon warriors arrived in 1350; others say they simply adopted a different culture for burying the dead. The name San Agustin was given by Spanish chroniclers and missionaries.

When were the statues discovered?

One of the earliest accounts of the statues, at that time covered in foliage and largely hidden from view, came from a Spanish priest visiting in 1750; almost a century later, the statues were depicted in paintings.

But official bodies didn't show any interest until much later; in 1931 the area was named an archaeological park and in 1993, it was declared a national monument.

Unfortunately, in the interim period, the gold-rich sarcophagi and burial mounds were subject to looting. Farmers ignorant of the statues' value also used torsos to fortify walls and heads even became doorstops.

Were these figures a symbol of sadness?

Although largely concerned with the deceased, a sentiment of celebration shrouds the statues. Death was seen merely as a passage to another life and, like so many pre-Columbian civilisations, relatives were keen to safeguard their loved ones' journeys.

The San Agustin people also had a connection with nature that's irresistibly admirable; human faces are etched onto the rocky riverbed of the Lavapatas Fountain, and images of animals are found in every tomb.

Stare long enough into the eyes of these idols and some rationale about their past might become apparent. But mostly it's a mystery, cast deep in the rock.

How to get there

The Ultimate Travel Company (theultimatetravelcompany.co.uk; 020 3051 8098) can arrange a 16-day trip to Colombia, visiting Bogota, San Agustin, Pereira, Cartagena and Tayrona National Park for £4,721 per person. Price includes international and domestic flights, transfers and accommodation, based on two people sharing.