WIth no major halite deposits, or concentrated salt springs like those found in other parts of the world, salt in Scotland and particularly the Firth of Forth had to be collected from the sea. While commercial salt manufacturing in the area reached its heyday in the 16-18th century using the prolific sat mines to fuel its production, salt pan production was recorded starting in the 12th century with Royal Salt Pans being granted to the local abbys near Inverkething and a royal warrant for salt production beign granted to PrestonPans.
While it is likely that smaller salt works , or personal salt manufacturing occured before then it is not an area that has been well researched as current historians tend to focus on the more readily available 16th century