* Fears for historic texts as library burned
* Ancient city bears brunt of Islamist destruction
* United Nations "horrified"
Jan 28 (Reuters) - The burning of a library housing thousands of ancient manuscripts in Mali's desert city of Timbuktu is just the latest act of destruction by Islamist fighters who have spent months smashing graves and holy shrines in the World Heritage site.
The United Nations cultural body UNESCO said it was trying to find out the precise damage done to the Ahmed Baba Institute, a modern building that contains priceless documents dating back to the 13th century.
The manuscripts are "uniquely valuable and testify to a long tradition of learning and cultural exchange," said UNESCO spokesman Roni Amelan. "So we are horrified."
But if they are horrified, historians and religious scholars are unlikely to have been surprised by this gesture of defiance by Islamist rebels fleeing the ancient trading post on the threshold of the Sahara as French and Malian troops moved in.
"It was one of the greatest libraries of Islamic manuscripts in the world," said Marie Rodet, an African history lecturer at London's School of Oriental and African Studies.
"It's pure retaliation. They knew they were losing the battle and they hit where it really hurts," she told Reuters.
Turban-swathed Tuareg rebels first swept into Timbuktu back in April 2012 to plant the flag of their newly declared northern Mali homeland.
Before the occupation, Timbuktu and its ancient mosques and burial grounds had become an obligatory stop for budget backpackers seeking the desert experience and scholars looking for historical wisdom from rare Islamic texts.
Written in ornate calligraphy, these manuscripts form a compendium of learning on everything from law, sciences, astrology and medicine to history and politics, which academics say prove Africa had a written history at least as old as the European Renaissance.
For years, people came to experience what locals called "the mystery of Timbuktu". They also came for camel rides at the gates of the desert, boat rides on the Niger river to spot hippos, and to visit the city's famous mud-built mosques with their distinctive turrets and protruding timber beams.
But soon after the Tuareg invasion, the city of the 333 Saints fell under the sway of Islamist radicals. Bars and hotels closed and the tourists, already spooked by earlier incidents of abduction and murder by al Qaeda linked militants, stayed away.
CAMPAIGN OF DESTRUCTION
It was not long before the Islamists imposed severe Sharia law and set about a campaign of destruction of centuries-old Sufi sites that prompted international outrage.
Shrines, graves and mausoleums were attacked with pick-axes, shovels and even bulldozers. The bones of Sufi saints were dug up, and the hard-liners tore down a mosque door that locals believed had to stay shut until the end of the world.
The militants from the Malian Ansar Dine militant group that occupied Timbuktu (the name means Defenders of the Faith in Arabic) espouse an uncompromising version of Islam that rejects what it sees as idolatry and aims to destroy all traces of it.
In Timbuktu, their targets have been sites revered by Sufis, a mystical school of popular Islam which honours its saints with ornate shrines. At least half of 16 listed mausoleums in the city have been destroyed, along with a substantial part of the history of Islam in Africa.
A spokesman for Ansar Dine, asked to comment last year on the smashing of Sufi mausoleums in Timbuktu, said their actions were ordained by faith. "We are subject to religion and not to international opinion," the spokesman said.
Similar episodes have been recorded in Libya following the fall of Muammar Gaddafi, when Islamists used a bulldozer to dig up Sufi graves in a cemetery in the city of Benghazi.
Most notoriously, Afghanistan's ruling Taliban blew up two giant 6th century statues of Buddha at Bamiyan in 2001, despite outcry from around the world.
UNESCO Director-General Irina Bokova has made appeals for the warring parties to spare "Timbuktu's outstanding earthen architectural wonders". These include the Sankore, Sidi Yahia and Djingarei-ber mosques, the last Timbuktu's oldest, built from mud bricks and wood in 1325.
The origins of Timbuktu - the name is believed to derive from the words Tin-Boctou (meaning the place or well of Boctou, a local woman) - date back to the 5th century.
The site on an old Saharan trading route that saw salt from the Arab north exchanged for gold and slaves from black Africa to the south, blossomed in a 16th century Golden Age as an Islamic seat of learning, home to priests, scribes and jurists.
A 15th century Malian proverb proclaims: "Salt comes from the north, gold from the south, but the word of God and the treasures of wisdom are only to be found in Timbuctoo."
RUMOURS OF GOLD
It was rumours of gold that drove European explorers to cross the trackless sands of the Sahara to search for the legendary city, already known for centuries to local inhabitants who traversed the deserts on camelback and navigated the muddy brown waters of the Niger by canoes.
Some of these foreign explorers died of thirst in the desert or were robbed and slain by fierce Tuareg warriors, while Timbuktu's mirage-like renown - no doubt enhanced by thirst-crazed, feverish imaginations - reached glittering proportions in the consciousness of 19th century Europe.
Scottish explorer Gordon Laing was the first European to arrive in Timbuktu in 1826, but he did not live to tell the tale, perishing at the hands of desert robbers.
It was not until two years later that Frenchman Rene-Auguste Caillie became the first European to see Timbuktu and survive to recount what he saw. "I have been to Timbuktu!" he is said to have breathlessly told the French consul in Tangier after he staggered back from his epic Saharan journey.
But after all his dreams of glittering minarets and palaces filled with gold, Caillie was disappointed to find in Timbuktu what it has largely remained for centuries: a dun-coloured town in a dun-coloured desert.
"I had a totally different idea of the grandeur and wealth of Timbuctoo," he wrote. "The city presented, at first view, nothing but a mass of ill-looking houses, built of earth. Nothing was to be seen in all directions, but immense quicksands of yellowish white colour," he added.
This initial sense of disappointment for outsiders, the myth not matching reality, seems to have traversed the centuries.
Normally loquacious Irish rocker and anti-famine campaigner Bob Geldof is reported to have been somewhat underwhelmed when he arrived in Timbuktu during the 1980s. "Is that it?" he said. (Reporting by Bate Felix and Maria Golovnina, writing by Giles Elgood, editing by Peter Millership)