Few would be surprised to learn that the story of the First Thanksgiving is mostly a myth. The idea that the Massachusetts Pilgrims and their Native American neighbors broke bread together in 1621 to celebrate the bounty of their harvest reads like a tale for children.

In 1970, on the 350th anniversary of the Pilgrims landing at Plymouth, TIME took note of the myth’s staying power and the darker nature of the truth. “The Pilgrims do not deserve the sentimental image created for them by Longfellow and his contemporaries in the 19th century, when the name Pilgrim itself finally began to catch on,” the magazine observed. “They had to be, and were, considerably tougher to surmount the brutal odds threatening their survival—one aspect of the myth that has not been exaggerated. During the first winter, cold, disease and famine cut their number in half—13 out of the 18 wives who came on the Mayflower died.”

As shown in this clip from the new Ric Burns documentary The Pilgrims, which will premiere on PBS on Tuesday evening, the bounty of that ‘Thanksgiving’ meal is still historically significant, for marking the end of a period of deprivation–even if the Pilgrims never called it Thanksgiving or issued formal invitations to their neighbors.

Read more from the TIME Vault: Unshakable Myth

Get our History Newsletter. Put today's news in context and see highlights from the archives. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Lily Rothman at lily.rothman@time.com.