This list is, of course, grossy incomplete. As more lore gets built into the world more will be added here. I have mostly focused on fleshing out the details of the southern half of Tarleaux, because that is where the campaign will start (and perhaps stay).
1024 Summer 3 Monday: The Countesses of Ikhil lead a rebellion against Barston, which had kept Ikhil as a vassal state for the previous century or so. Within a month they establish Ikhil as its own sovereign nation.
1317 Autumn 5 Lunday: The world's preeminent biologists, herbalists, arcanists, and other experts convene a council in the capital of Barston to discuss the phenomenon that has started being referred to as The Blight: a sudden and severe drop in the ability of all plant life in the world to produce healthy seeds, pollen, rhizomes, and other reproductive organs. The council can find no disease, curse, or other explanation and is unable to recommend any specific solutions or mitigation strategies.
1317 Winter: The world suffers through severe food shortages as harvests of crops for which the edible component is the reproductive organ are far below normal.
1318 through the present: The lack of grain stores cascades to livestock needing to be culled when they cannot be fed. Natural ecosystems being to fail as shortages move up the food chain. Widespread famine causes migrations from areas that are no longer able to provide for their populations' basic needs to places that still can. Spellcasters, which have always been rare, become prized for their ability to create food magically.
1341 Winter 2 Wednesday: King Reginald III of Barston dies without producing an heir, ceding leadership of the nation to his younger brother, Ranwid I.
1342 Spring 5 Tuesday: The campaign begins.