The Southern Reaches ("TSR" - heh ... ) is a pretty broad-brush campaign setting. The intent, as I understand it, is for GMs to develop it to taste.
To assist folks, I thought I'd put together a brief timeline of the Reaches, measured against an implied, but not required "Current Year", or CY:
-1,100 CY: Last Fey vanish beyond the Veil.
-900 CY: Competing bands of Orcs and Stagli Riders begin to range through the Reaches
-500 CY: Empire of Irwan formally annexes the Reaches.
-490 CY: Domestication of the lowlands of the Reaches begins in earnest.
-200 CY: Lashingport declared Imperial Territory by royal edict.
-75 CY: Purdagi Horde lands at Wholestone and proceeds to rampage.
-15 CY: The Count of the Mists convenes the Fey Court on the Reaches side of the Veil.
-12 CY: Lady Tagia betrothed to Lord Firthal Drum.
-12 CY: Lady Tagia marries Lord Beleghir.
CY: Current Year
The item at -15 CY is my own addition, and the -900 CY entry my speculation based on the text; the rest is "canon". All years approximate according to the text.