Tracing the history of book-banning presents obvious difficulties: Written history, especially prior to the most recent centuries, is far from complete and reliable, and recording an act of censorship under a regime given to censorship is an even more troubled proposition.

Certain acts of censorship have doubtless been lost to history, while certain legendary ones — such as the notorious burning of the Library of Alexandria by Caliph Omar in A.D. 642 — have been called into question by historians. After all, historians are not always free from ulterior motives, and accusing political rivals and despised former regimes of anti-intellectual crackdowns may have allowed some ancient catalogers to control the narrative in favor of their own preferred rulers.

Yet it’s clear that attempts to control and squelch literary speech have existed nearly as long as published literature itself has. The American Library Association’s yearly Banned Books Week shines a light on how censorship and restriction of speech continue to affect readers and authors in America today, but the roots of book banning stretch deep into the past.

Here are six historical moments when book censors won major victories, restricting access to the written word:

Qin Shi Huang burns Confucian writings (~221-210 B.C.)

A powerful ruler who consolidated China’s empire and standardized its language, bureaucracy, and calendars, Qin Shi Huang left an indelible mark on the history of his people. He also is believed to have resented the scholars who kept memories of Confucian tradition alive. As he came to power, Qin Shi Huang supposedly had many Confucian texts destroyed, fearing that they would be used to undermine support for his rule; he later allegedly ordered hundreds of scholars buried under suspicion of spreading dissent. Some historians now question this narrative, which is laid out in the Records of the Grand Historian, suggesting that it’s more likely that Confucian writings were lost when a fire destroyed much of the imperial library during the fall of the Qin capital. The truth may always remain a mystery.

Girolamo Savonarola holds bonfires of the vanities (1497-98)

The Florence book burnings of the fanatical priest Savonarola were so notorious, they’ve made “bonfire of the vanities” a common cultural reference — Tom Wolfe titled a novel after the event. In addition to “immoral” books, the bonfire was meant to destroy other luxuries that might lead people into perceived sin (art, fancy clothes, cosmetics, and so on). Though Savonarola was a Dominican priest, he had formed a political party that held significant power in Florence, giving his condemnations of certain texts and artistic creations overtones of governmental as well as religious power.

Index Librorum Prohibitorum established by Pope Paul IV (1559)

The Catholic Church’s power rivaled that of empires in 1559, when it created a list of books banned for its adherents, the Index Librorum Prohibitorum. New editions of the Index continued to be published until 1948, and it wasn’t until nearly 20 years later that it was finally taken out of effect. That’s over four centuries of official religious regulation of Catholics’ reading materials. At various times, influential and brilliant works by authors such as Immanuel Kant, Simone de Beauvoir, and John Milton were placed on the list.

The Meritorious Price of Our Redemption by William Pynchon banned in New England colonies (1650)

Considered the first book to be banned in the New England colonies, The Meritorious Price of Our Redemption was a critique of Puritanism that so outraged Pynchon’s fellow colonists that he was compelled to return to England. Copies of the book were burned in Boston, and Pynchon himself was accused of heresy in the Massachusetts Bay Colony. Book banning would go on to have a long and troubled history in the so-called New World.

The Sorrows of Young Werther banned in several European jurisdictions (1774)

While, in the history of book-banning, political or religious motivations often underlie censorship, the banning of Johann Wolfgang von Goethe’s The Sorrows of Young Werther introduces a public health angle. Goethe’s slim novel follows the romantic travails of a passionate young man — culminating in Werther’s gunshot suicide after he is rejected by his beloved. The novel became wildly successful, so much so that its popularity was designated “Werther fever”; young people reportedly began to imitate Werther’s fashions and made pilgrimages to the grave of a friend on whom Werther was believed to be based. Authorities were so concerned about reports of copycat suicides that several European cities and countries, including Denmark and Austria, banned or regulated the book. It’s unclear how many actual copycat suicides took place, but the bans went ahead regardless.

Dr. Thomas Bowdler publishes expurgated Shakespeare (1807)

Like Savonarola, Dr. Bowdler popularized a new term in the vocabulary of book censorship: “bowdlerize.” Bowdler’s 1807 edition of 24 collected Shakespeare plays — which is believed by many to have been edited by not by Bowdler, but by his retiring sister Harriet — remains infamous for attempting to make Shakespeare’s dramas palatable for polite domestic society by generously excising any vulgar or obscene portions. The 1807 edition was followed by later volumes giving the same treatment to more of Shakespeare’s works; the series was entitled The Family Shakspeare. That’s right: Shakespeare himself was given the bad-for-family-values treatment back in the day. At least the Bowdlers were able to see the value in reading and teaching Shakespeare despite his profane turns — but unfortunately the Bard isn’t really the Bard without some bawdy jokes.