"Our ceilings are not very tight," says Abdel Haidara of the houses in his native Mali.

He's talking in Arabic at a Monday afternoon lecture at the Library of Congress in one of the library's more ceremonial rooms. Curiously, there is sign of what looks like a little water damage above an arch window behind him.

In a big library with small problems, he's talking about small libraries with big problems. Haidara is the curator of the Mamma Haidara Commemorative Library, a private holding of some 5,000 ancient manuscripts in Timbuktu, the legendary city of Mali. Over the 13 generations that his family has held this trove of manuscripts, water damage has been only one of a Jobian list of predations. There was a serious fire, and a building collapse, and in 1973, a drought in Mali that so stressed the already impoverished people that pilferage became a serious threat. And throughout the ages, dating back to the 16th century when his "first grandfather" started the collection, there has been a long and debilitating war with insects, heat and dust.

But the collection has survived, and in conjunction with the Smithsonian Folklife Festival, which begins today (and includes a focus on Mali), a small sample of texts from the Haidara library is on view at the Library of Congress. The delicate pages were not bound, but stacked and stored in tooled-leather cases. Documents on display, selected from some 23 books brought to the Library of Congress to be microfilmed, include works on astronomy, mathematics, Islamic law and business ethics. The script is Arabic, but with a variety of calligraphic styles, and in some cases ample marginalia that testify to their long use in everyday study.

It is an unprepossessing exhibit, and like most exhibits of documents, there is something inert about pages of old script lying under glass. The collection, however, is anything but inert, and is at the center of great scholarly excitement. A wall text says these manuscripts may lead to a reevaluation not just of African history, but of world history.

"What's been happening in Mali in the last decade has been an emergence of information that heretofore was previously unknown," says Chris Murphy, an area specialist in the library's African and Middle Eastern division who helped curate the exhibition. That includes information about local kingdoms, local medicine, local literature including epics and poems, and firsthand accounts of the trade in slaves, salt and gold that made Timbuktu a center of the Islamic world to rival Cairo and Istanbul.

There's a lazy habit, among people who think history began with the Greeks and ended with Americans, of thinking of African "civilization" as a thin ribbon of cities and cultures running along the Mediterranean Sea and down the Nile. Conveniently, it is the same Africa that was most engaged with Europe and the Near East. But that Africa was also intimately connected with Saharan and sub-Saharan Africa. And cities like Timbuktu, where an important overland trade route joined canals leading to the Niger River, weren't backwaters or outposts of North Africa; they were the centers of their own civilizations, which reached even further into the center of the continent.

Although they are written in Arabic script and many of them deal with Islamic law and religion, the Timbuktu libraries aren't filled merely with copies of Arabic texts that circulated throughout the Islamic world. Rather, they contain a full, rich and particular history of another Africa, with its own kingdoms, literature and history. This Africa is not lost to the vagaries of oral history, but it remains mostly unknown. Little of its history has been translated.

Individuals, governments and outside agencies have begun to focus efforts on preserving an estimated 1 million or more ancient documents scattered around western Africa. In Timbuktu alone there are some 22 private family libraries, few (if any) benefiting from modern preservation. In the environs of Timbuktu, as many as 100 different families hold ancient documents, and stories are told of more nomadic families, farther afield, that have buried boxes of priceless texts and then moved on, never to unearth them.

If there was a standard way to graph the importance of a cultural object multiplied by its vulnerability to destruction, the manuscripts of Mali would be off the charts. Mahmoud Abdou Zouber, an adviser to Malian President Amadou Toumani Toure (who was on hand to celebrate the opening of the Library of Congress exhibition yesterday), has been working to save these texts since the 1970s. He approached one family, which held an important trove, in 1978; not until 1982 was he ushered in to see the collection. After a brief glimpse, he was asked to come back in a week. When he did, the door to the library had been walled over. That was, he believes, the family's way of showing its reluctance to deal with government officials who, they fear, will take their holdings from them. Suspicion prevails.

"It is rare to find owners of manuscripts who are open to approach," says Zouber.

Haidara, who was inspired by his father to take an active interest in preserving his family's holdings, including fundraising and cataloguing, says many families aren't aware of the immense importance of what they hold. Manuscripts are passed on, generation to generation, because of their sentimental and emotional importance, like quilts or heirlooms. But often no one in the family can actually read them, and storage is haphazard.

Timbuktu, once a teeming city of merchants and traders and a center of scholarship, is now a dusty town of some 20,000 people. It was founded in the 11th century, and was central to a succession of peoples and empires -- the Tuareg, Mali, Songhai -- before Morocco sent soldiers overland to sack it late in the 16th century. It was known to Europeans, but so remote as to seem legendary. Not until the 19th century did Europeans return with extensive firsthand accounts of it. Even a Mali tourist Web site says, "Many are surprised to find it actually exists."

"It's like Rust Belt cities in the Midwest," says the Library of Congress's Murphy. "They once had great cultural institutions."

A 1998 visit to Timbuktu by Harvard professor Henry Louis Gates Jr. (to work on the documentary "Wonders of the African World") attracted attention to the plight of the Mali manuscripts. And that attention helped Haidara raise funds to build a small library with better storage facilities, a reading room and computers. But Haidara's efforts remain the exception and there's a sense of urgency among scholars and curators.

"The needs are simply immense," says Murphy. A massive amount of information produced by human beings is at risk, he points out.

Where that information leads is anyone's guess. But a wealth of insights into how Islamic law and local customs coexisted has immediate political relevance; and the existence of untranslated literature, local poetry and epics appeals to the most fundamental curiosity of man: to know each other's stories.

Ancient Manuscripts from the Desert Libraries of Timbuktu will be on display in the South Gallery of the Great Hall in the Library of Congress's Jefferson Building through Sept. 3. The library, on First Street SE across from the U.S. Capitol, is open 10 a.m. to 5 p.m. Monday-Saturday. Admission is free. For more information visit www.loc.gov/exhibits.

An astronomy text depicting the rotation of the heavens, copied in 1733, is one of many manuscripts -- a number of them ravaged by time -- from the legendary city of Timbuktu, Mali, on display at the Library of Congress.