(Perhaps this already exists) A comparable project to the AM Chronology Project, but, a greatest hits history book of the 13th+14th century feels like a really useful thing to have. Eg, what changes year by year, are there any noteworthy inventions or artistic occurrences*, are there any new kingdoms or cultural movements. The sort of thing where you’re running a saga and you forget that the Mongols should have invaded your story’s general territory a few years ago.
I do think the ideal version of this tool is one that could be sorted chronologically AND regionally, so probably not a PDF as much as a database of events, tagged by region (and perhaps personalities).
*Acknowledging that we probably don’t have hard dates for a lot of things, this is probably more in the order of “First mention of the treadwheel crane existing in [region].”