Real history, folklore used in J.K. Rowling's wizarding world tale set atop Mount Greylock
J.K. Rowling's Pottermore story established Ilvermorny, the North American Wizarding School, to be in the heart of Mount Greylock, but not everything in the story was pure fiction.
Some aspects of the story were borrowed from local history and folklore.
The tragedy of Elias Story
In the context of the story, protagonist Isolt Sayre masquerades as a man to get passage aboard the Mayflower, using the fake name "Elias Story." When Sayre left Plymouth, Mass., as "a witch was unlikely to find many friends among the Puritans," she let her former shipmates believe Story died in the harsh winter.
The real Elias Story was a servant who came to the new world under the care of the Edward Winslow family. According to historian Caleb Johnson, he did not sign the Mayflower Compact, suggesting that he was under the age of 18 or 21 at the time.
Story is buried at Cole's Hill Cemetery at Plymouth. His name is carved into a shared headstone honoring those who died during the first winter.
North Central beginnings
Rowling invented several new creatives in the Pottermore tale, the deadliest of which were the Hidebehinds. According to the story, "the Hidebehind is a nocturnal, forest-dwelling spectre that preys on humanoid creatures. As the name suggests, it can contort itself to hide behind almost any object, concealing itself perfectly from hunters and victims alike."
This description is perfectly in line with the Hidebehind legends in American folklore, who were known to ambush and devour unsuspecting humans, especially forest walkers and lumberjacks.
According to "Giants, Monsters, and Dragons: An Encyclopedia of Folklore, Legend, and Myth," published by W. W. Norton and Co., the lore originates from Wisconsin and Minnesota during the 19th and early 20th centuries.
Apparently the Hidebehinds are a part of a group of mythical beasts called the "Fearsome Critters," which, according to the book have "exaggerated proportions and activities that not only explained the weird noises of the lonely landscape but also provided some amusement at camps."
Whether it be in mythology or in the world of Harry Potter, there are plenty of reasons to fear the forest, especially at night.
The character William Sayre is barely discussed in the Pottermore story, but he had great impact as Isolt's father. In the story, Sayre dies trying to protect his family, which only makes it all the more cruel when his murderer, Gormlaith Gaunt uses his name to gain passage on the vessel Bonaventure.
In 1634, a merchant vessel by the name of Bonaventure set sail for Virginia, with one William Sayre on board. According to the ship's manifest, Sayre was 58 years old, which is an ideal age for Gaunt, given that Isolt was 31.
Little else is known about Sayre.
Hag's Glen is a real place
Gaunt raised Isolt in a mysterious location dubbed "Hag's Glen" which you can visit if you're ever in Ireland.
The glen is right next to Carrauntoohil, which is the highest peak in Ireland. Like Greylock, it is home to many trails, and is a popular tourist location. According to summitpost.org, no special equipment is needed to climb the mountain, but there have been a number of deaths due to underdressed tourists.
Gaps in the records
Isolt's love interest, James Steward, is also based on a real-world Plymouth settler.
James Steward came to America aboard the Fortune, the second English ship sent to Plymouth. According to a genealogical profile compiled by Plimoth Plantation and the New England Historical Genealogical Society, Steward received one acre of land in the land division of 1623, which indicated that he had no family. However, his name was missing from the updated 1627 division of land, which indicated that he either left the colony or died.
There are no records of his time or place of death.