Don't forget literacy patterns.
Of course I would think of that, but for a less obvious reason. For a while, one of the fifth grade teachers had me come in and teach a 5-week unit on calligraphy for their required handwriting unit. (Students are more apt to do all the mechanical exercises more willingly if the end product is more interesting.) We spent a week on the development of the Western alphabet, starting with Egyptian hieratic writing. There are some fascinating patterns connected to alphabet development and the ebb and flow of literacy, which doesn't always follow our historical model of the spread of civilization. Commerce, yes.