Ali Baba and the Forty Thieves is a fairy tale from Arabian Nights.
Ali Baba and his brother find the golden treasure in the thieves’ cave, which can only be entered when the password “Open Sesame!” is spoken.
Ali Baba’s brother is trapped in the cave and when the thieves catch him, he’s hung up and quartered. They also realize he has an accomplice, and set out to find Ali Baba.
When the thieves attempt to discover where Ali Baba lives, the first thief marks his gate with a chalk mark, but Ali Baba’s trusted servant marks all the surrounding gates.
The second thief cuts a chunk out of Ali Baba’s gate, but the trusted servant again marks all the surrounding gates in the same way.
Finally the leader of the thieves attempts to kill Ali Baba and sneaks in all the thieves hidden in oil barrels, but Ali Baba’s trusted servant smothers them with heated oil.
The shawl shows the golden treasure, the gates (the first set marked with chalk, and the second set with a chunk missin), and the burning oil flames. It is knit from the top down, in four quarters (half an octagon).
A version of the fairy tale is available on my blog.