What is Glamis?

In William Shakespeare's tragic play Macbeth, the titular character is referred to as the "Thane of Glamis" from the very outset. This is a reference to a specific location in Scotland. Glamis is the name of the area that Shakespeare's Macbeth rules, and it is located in the eastern part of Scotland in the county of Angus. While Shakespeare situates his King Macbeth in Glamis Castle, the real life Macbeth didn't have any ties to it. However, the castle does have ties to other famous people, as it was the childhood home of Queen Elizabeth II, the Queen Mother.In Macbeth, Shakespeare uses the name of real people and places from history, like Glamis and Macbeth, but he plays with the true history of them. His version of Macbeth is far more sensational than that of the real Macbeth, and Shakespeare populates his Scotland with far more supernatural elements (although the real Glamis Castle is said to be one of the most haunted places in Scotland). It is the site of the murder of King Malcolm II (which probably inspired Shakespeare to situate the murder of Duncan here as well). Situating his play in specific locations that his audience would be familiar with presents a much more attractive, believable tale.
https://theculturetrip.com/europe/united-kingdom/scotland/articles/a-tour-of-macbeths-scotland-in-13-places/