One moment the landscape feels like the hills of Devon or Shropshire. Cows browse by farm gates on gentle slopes and grey skies threaten rain. Then flowering trees flash beside the road. A poncho-wearing donkey-rider trots amiably by. We stop for a snack of soft cheese and sugar-cane jelly at a makeshift stall; the farmer's little daughter wears a cow-shaped hat. Humans and animals blur a lot in this story.
Driving north from Bogotá through the province of Cundinamarca, the moorland grows steeper, wilder – more Wales or the Highlands. Once inside a national park, our group sits down with a friendly Venezuelan family in a modern version of the circular thatched building that served the Muisca – the dominant indigenous people here – as village hall and council chamber. It's pelting down outside now, as a guide spins tall tales of lovestruck cannibals and even UFO visitations – all totally fanciful and romantic, British Museum curator Elisenda Vila Llonch assures us afterwards – about the nearby, sacred focus of our quest. To her, "the reality behind the El Dorado legend is so much more intriguing than the myth".
For that – an almost 500-year-old legend, and the blazingly material riches that gave rise to it – accounts for our presence on a damp, late rainy-season day in this hut, in this park, and in the north Andean uplands (almost 3,000m high) of Colombia. Next Thursday, the British Museum will open its exhibition, Beyond El Dorado: power and gold in ancient Colombia. It has borrowed more than 200 treasures from co-organiser, the Museo del Oro (Gold Museum) in Bogotá – "the best collection in the world of pre-Colombian gold," confirms Elisenda Vila – and supplemented them with its own ample holdings of the gorgeous artefacts via which leaders and prophets summoned and channelled the forces of nature.
Dazzlingly crafted bats, jaguars, fish, toads or caimans served as their iridescent spirit guides. "It's a wonderful opportunity to be in London again," says Maria Alicia Uribe, the Gold Museum's director, "and to put our collections together." The last time Colombian gold came to London – on a much smaller scale – was in 1978. Elisenda Vila hopes that the show can dispense with the delusions, but still present a tale that compels: "It tells a story; it's about the people as well as the objects. For the exhibition, we've made a narrative broader than ever before."
Since the 19th century, the exquisite metallurgy practised over 2000 years (from around 500BC) byf half a dozen different ethnic groups among Colombia's plains, coasts, forests and peaks has acted as a showcase for the culture. "After independence from Spain, all the Latin American nations were trying to find their own identity," explains Uribe. Amerindian gold assumed "a very important role" here because Colombia lacked the monumental architecture of Mexico and Peru. Its closely-meshed network of trading tribes – who trafficked in gold, only panned or mined in specific areas, as well as crops and materials – had never coalesced into a centralised empire like the Aztecs or Incas. Thus "the gold work became a source of pride".
So it remains. Later in the trip, we visit provincial offshoots of the Gold Museum in the sultry, pastel-shaded colonial-era ports of Cartagena and Santa Marta on the Caribbean coast, home territory for the Zenu and Tairona peoples. I watch neatly uniformed crocodiles (or should that be caimans?) of schoolchildren taking tours around their ancient legacy. This isn't about bling and glitz, but a validation of pre-colonial culture and its various peoples – who, in differing proportions, will be direct ancestors for most of these kids.
Appalled by the 'idolatry' of the ceremonies in which gold regalia and implements played a solemn part, the Spanish conquistadors – who landed on the Caribbean coast in 1499 and had founded Bogotá by 1538 – mixed piety and profit when they seized sacred artefacts. "The Spaniards usually took the objects from the Indians and just melted them," says Uribe. "And they looted tombs, which they found easy to identify." The goldsmith's art – both refined and specialised, with different virtuosi in charge of particular techniques – may have endured in other media. As for the ceremonies that gave gold its ritual and religious meaning, Elisenda Vila thinks that "they survived for quite a long time" after the European conquest: "maybe 100 years; but of course they were in secret".
As our park guide ends his spiel and the rain eases off, I can see how those secrets endured. We climb higher, through highland tropical vegetation where familiar-looking ferns and heathers surreally entwine with orchids and other exotics (to a British eye). Then, almost magically invisible even from a short distance, a bowl of dark water comes into view. This is Lake Guatavita: the nearest that we or anyone will ever get to the source of El Dorado.
Since the early 16th century, rumours of a kingdom awash with gold and of its gold-enrobed ruler – El Dorado, the Golden One – had filtered back to Spain and Europe. Early historians such as Fernández de Oviedo embellished the prodigal splendour of lands where gold seemed as common as salt. At the heart of these come-hither tales lay the image of a gold-powdered chieftain who, flanked by priests and musicians, sails on a raft into the centre of a sacred lake, in whose waters he deposits glittering treasures as a tribute to the gods. In 1636, the Bogotá chronicler Juan Rodríguez Freyle gave the legend its most vivid written shape.
The myth which took root in Europe concealed, as myths tend to do, a kind of truth. "In reality, there were probably many rituals in different locations," suggests Elisenda Vila. At least five lakes in this region, not just Guatavita, may have held a ritual significance for Muisca cosmology. Caves also attracted offerings. Half-glimpsed through European eyes, these ceremonies brought to mind sun- and moon-worship, or maybe rites of dynastic succession.
More likely, they marked the changing seasons, gave thanks for the cycle of the year and served to maintain the equilibrium of nature as gold returned to the earth that bred it. In the Gold Museum, proudly solitary in its own darkened shrine, stands the intricately-worked Muisca raft. Found in a cave at Pasca, south of Bogotá, in 1969, housed in a clay pot with a grinning, enigmatic anthropomorphic face, this raft seems to depict in gold a chief and his attendants attired for the 'El Dorado' ritual. This ultimate icon of Colombian sacred metallurgy doesn't travel, not even to the British Museum. "We didn't even ask for it," says Elisenda Vila.
All myths aside, vast quantities of holy gold did drop into Guatavita and other lakes. And so the foreign plunderers began their unholy quest to recover it. Drainage attempts at Guatavita began in 1580s and continued (with a British company to blame) right up to 1910. A channel was even cut to empty the bowl; today, the lake's depth of 40 metres may be a mere third of its 16th-century level. Even if the scavengers got the story and its meaning wrong, they still went home with all-too-solid loot: 6,000 cargas (donkey loads) for one mission, a chronicler records. Under louring skies, with the summit-dotted moors rolling away behind, I gaze down into this ring of black water and try to connect it with five centuries of garish, greedy fantasy.
Back in the Gold Museum, often thanks to surviving objects found in the tombs of powerful figures (you can take it with you, the Amerindians believed), we can savour as religious art what the lake raiders viewed as mere lucre. Colombian goldsmiths not only worked wonders with their material – hammered and drawn into delicate filigree detail, or else cast in clay moulds using the tricky, high-risk 'lost wax' method. They spanned a vast array of styles from the boldest abstraction to eagle-eyed naturalism and whimsical fantasy. "After working for such a long time with this collection," says Uribe, "one of things that still amazes me is its diversity."
Above all, in these cultures where the community leader took on the attributes of powerful beasts and the spiritual specialist ('shaman', if you like) flew like a bird into trances of enlightenment, the golden animals fix and return your gaze. Hybrid, fabulous or realistic, they cross boundaries and merge worlds. There are the science-fiction bat-men of the Tairona, lords of the underworld who command the realms of night; the Zenu caiman, amphibious traveller between elements and guardian of human welfare; the ethereal winged fish from San Agustin that, again, elegantly slides through spheres; and the all-powerful jaguar, depicted everywhere as stylised breastplate or almost-cute moggy-style statuette. In shiny facsimile, the big cat lent to big chiefs its top-of-the-food-chain glamour and dread.
Almost as ubiquitous, and a poignant link between Colombia's ancient glories and modern torments, are the poporos. These gourds, sometimes cast in gold, contained crushed lime from sea-shells. With the aid of finely decorated golden sticks, the shaman consumed it in order to enhance the effect of chewing coca leaves. Colombian coca – E novogranatense – played a ritualistic role as a stimulant boost to vision and stamina from earliest times. Indeed, the Gold Museum holdings began in 1939 when the Banco de la Republica – still the museum's patron – refused to sell on a fine Quimbaya gold poporo.
Outside Colombia's borders, the gold – especially in the British Museum, with its public that, as Uribe notes, "comes from everywhere" – perhaps has an extra symbolic role. It will help set the seal on a decade of canny and strenuous public diplomacy that has seen Brand Colombia (a body which really exists; we lunched at its offices in Bogotá) work smartly to burnish the national image. Four decades of vicious interconnected strife between the state, the narco-barons, leftist guerrillas and rightist paramilitaries have cost almost a quarter of a million lives.
Every figure about cocaine production in the Andes comes with a health warning; all the statistics are deeply politicised. However, since Bill Clinton and then Colombian President Andrés Pastrana kicked off 'Plan Colombia' in 1998, a fiercely enforced policy of eradication and interdiction – with crop-spraying condemned as "ecocide" by some – has meant that the nation now produces around 40 per cent of the world's cocaine rather than 80 per cent. Since the millennium, peace and hope have returned to many regions. Bogotá now boasts a lower homicide rate than Washington DC or Rio de Janeiro. But the famous Andean 'balloon effect' (squeeze one spot, and another expands) means that, according to the latest UN figures, Peru has taken over as the world's top cocaine producer.
Colombia's promoters had to scale their own mountain of modern myth. Slowly, but surely, many people overseas have shed their prejudice and downright fear to appreciate the country's outstanding human, cultural and natural wealth (it's the second-most bio-diverse country on Earth, after Brazil). Beyond El Dorado, which shatters or revises one long-standing fable but finds an equally alluring reality, can maybe stand as a microcosm of that long, tough process of national re-invention.
Meanwhile, President Juan Manuel Santos has, since November 2012, reversed the no-negotiation policy of his predecessor Álvaro Uribe to engage in direct talks with the leadership of the much-enfeebled left-wing guerrilla army, Farc. Like the even more ruthless right-wing brigands of the now-demobilised AUC, the Farc long ago became a drug-farming, extortion and kidnap operation under a thin veneer of ideology. However, as Swedish investigator Magnus Linton puts it in his hair-raising new book Cocaina, "the white powder didn't give rise to the country's injustices and war; it just multiplied them".
Those injustices – many rooted in the historic impunity of large landowners in remote provinces where the state's writ barely runs – surfaced again just prior to our visit. Small farmers blocked roads and battled police in protest against falling incomes and competition from cheap imports. Some observers took those clashes as a sign of progress. This wasn't another covert bid to derail the state by a narco-lord or shadowy guerrilla chieftain, but a popular plea for a functioning government to support its citizens' welfare: almost normal politics.
In former coca-bush hotspots such as backwoods Putumayo and Antioquia, by the way, new reports suggest that one-time growers have switched to an activity that can yield (according to a rural police chief) 19 times more cash per kilo than the once-mighty leaf. They have become unlicensed gold miners. Authorised extraction also booms. If the radiant skills of their forebears revive as well, then more power to their picks and pans. Colombia's gold can shine again.
Beyond El Dorado: power and gold in ancient Colombia, sponsored by Julius Baer and supported by American Airlines, is at the British Museum, London WC1, 17 October to 23 March, 2014. Boyd Tonkin travelled to Colombia with American Airlines