When al-Qaida Islamists invaded Mali, and then Timbuktu in 2012, among their targets were priceless manuscripts—books that needed to be burned. But the damage could’ve been much worse if not for men like Abdel Kader Haidara, who risked their lives to protect the medieval works. He and others succeeded in smuggling out 350,000 manuscripts, proving not only how much the books were valued, but also the lengths to which ordinary people were willing to go to save them. It was a remarkable victory in the long history of books threatened by would-be arsonists—and a relatively rare one at that.

Books and libraries have been targeted by people of all backgrounds for thousands of years, sometimes intentionally and sometimes as a side-effect of war. In 213 B.C., Chinese emperor Qin Shi Huang (more widely remembered for his terracotta army in Xian) ordered a bonfire of books as a way of consolidating power in his new empire. According to historian Lois Mai Chan, “His basic objective was not so much to wipe out these schools of thought completely as to place them under governmental control.” Books of poetry, philosophy and history were specifically targeted, so that the new emperor couldn’t be compared to more virtuous or successful rulers of the past. Although the exact amount of information lost is unknown, Chan writes that the history genre suffered the greatest loss.

Qin was only one in a long line of ancient rulers who felt threatened enough by the ideas expressed in written form to advocate arson. In Livy’s History of Rome, finished in the 1st century A.D., he describes past rulers who ordered books containing the predictions of oracles and details about celebrations like the Bacchanalia be outlawed and burned to prevent disorder and the spread of foreign customs; philosophers Giordano Bruno and Jan Hus both took positions counter to the Catholic church, the former for his work on Copernican cosmology, the latter for attacking church practices like indulgences. Scholar Hans J. Hillerbrand writes that the executioner charged with killing heretics like Bruno and Hus was often the same person who put flame to their books.

But for Rebecca Knuth, author of Libricide: The Regime-Sponsored Destruction of Books and Libraries in the Twentieth Century and Burning Books and Leveling Libraries: Extremist Violence and Cultural Destruction, Qin and religious leaders like him are only a small part of the early book-burning equation. “A lot of ancient book burning was a function of conquest,” Knuth says. Just look at one of the most famous examples of burning, the destruction of the Library of Alexandria. The famed building had its contents and structure burned during multiple periods of political upheaval, including in 48 B.C. when Caesar chased Pompey to Egypt and when Caliph Omar invaded Alexandria in 640 A.D.

What changed everything was the printing press, invented by Johannes Gutenberg in 1440. Not only were there suddenly far more books—there was also more knowledge. “With the printing press you had the huge rise of literacy and modern science and all these things,” Knuth says. “And some people in authoritarian regimes, in a way they want to turn back the effects of the printing press.”

According to Knuth, the motives behind book burning changed after the printing press helped bring about the Enlightenment era—though burning through the collateral damage of war continued to arise (just consider the destruction of the U.S. Library of Congress during the War of 1812 or all the libraries destroyed across Europe during World War II). People saw knowledge as a way to change themselves, and the world, and so it became a far more dangerous commodity, no longer controlled exclusively by the elite. What better way to reshape the balance of power and send a message at the same time than by burning books?

The unifying factor between all types of purposeful book-burners in the 20th century, Knuth says, is that the perpetrators feel like victims, even if they’re the ones in power. Perhaps the most infamous book burnings were those staged by Adolf Hitler and the Nazis, who regularly employed language framing themselves as the victims of Jews. Similarly, when Mao Zedong took power in China and implemented the Cultural Revolution, any book that didn’t conform to party propaganda, like those promoting capitalism or other dangerous ideas, were destroyed. More recently, the Jaffna Public Library of Sri Lanka—home to nearly 100,000 rare books of Tamil history and literature—was burned by Sinhalese Buddhists. The Sinhalese felt their Buddhist beliefs were under threat by the Hinduism of Tamils, even though they outnumbered the Tamils.

Even when the knowledge itself isn’t prevented from reaching the public, the symbolic weight of burning books is heavy. “Books are not absolutely dead things, but do contain a potency of life in them as to be as active as that soul was whose progeny they are,” wrote John Milton, author of Paradise Lost, in his 1644 book Areopagitica. “Who kills a man kills a reasonable creature… but he who destroys a good book, kills reason itself—” an idea that continues to be espoused in modern culture, like in Ray Bradbury’s Fahrenheit 451.

“A book is a loaded gun in the house next door,” one character warns another in Bradbury’s story, arguing for why they must be burned and their knowledge erased. “Who knows who might be the target of the well-read man?”

Or, as author Barbara Tuchman said in her 1980 address at the Library of Congress, “Books are the carriers of civilization. Without books, history is silent, literature dumb, science crippled, thought and speculation at a standstill. Without books, the development of civilization would have been impossible.”

Today, with new technological advances offered by the Internet, the possibility of digitizing written documents seems to offer books a new immortality. But not so fast, Knuth says. “We have technology to preserve so much knowledge, we just have to be careful. If you don’t keep morphing it to an updated form of technology, it doesn’t matter if you made copies if you can’t access them.”

This is a problem archivists at the Smithsonian Institution regularly tackle, including electronic records archivist Lynda Schmitz Fuhrig.

“There are software companies that have gone away or gone out of business, and some of that software just stops being used,” Schmitz Fuhrig says. “And there’s not only the issue of software, but also hardware and operating systems that may not work with these older files.”

The archivists try to use formats that have been around for a long time and stood the test of time, like PDF for documents, but even keeping up with the changing technology doesn’t guarantee safety. Schmitz Fuhrig says one of the biggest challenges now is storage space. “A few years ago we were talking about gigabytes and then terabytes and now we’re getting into the area of petabytes.”

Even though the technology exists, transferring written documents to digital archives requires time and money—resources that aren’t always available. Sometimes doing so is counter to the beliefs of whoever happens to be in power. Just consider that under President George W. Bush EPA libraries were threatened with closure in 2006, spurring the American Library Association and scientists working at the EPA to put pressure on Congress to ensure the EPA’s budget could cover the cost of maintaining the libraries (although some libraries were closed, they reopened in September 2008). Or look at the scientific research documents that were locked away or destroyed under the Stephen Harper government in Canada in 2014, which had a chilling effect on the topics that could be researched and the studies that were published. As scientist Steven Campana, who spent decades working for Canada’s Department of Fisheries and Oceans, told Smithsonian.com, “Although we still kept our jobs, we basically were prevented from actually doing any science.” Though the methods may be different (and less visible) than in the past, the results are the same: knowledge is purposefully taken from the public.

Technology has undoubtedly changed the way we share and save information, but Knuth argues that the core motivations for book burning, in whatever form the act takes, remain the same: prioritizing one type of information over another.

“That’s why power is so scary,” Knuth says. “Because power allows you to put into effect the logic of your own beliefs.”