I am still working on my campaign in the past of Faerun so I open here a scroll just to ask some questions.
I am working currently on the tiny links between Chondath and Sembia and their common past. I have a question on the year 680 DR
680 DR [Year of the Long March] Chondath mercenary forces begin the long march home after ensuring the collapse of the second Untheric Empire. »
Why those mercenaries have left Unther ? Because they have been hired by the country to fight their local enemy such Mulhorand or the league of Samathar ?
Or they came from some border fighting with the Chondath to the control of the Chondalwood may be ?
I did a fair bit of work on the old empires so ill see if i can find you an answer (or give you my interpretation of it). But it'll have to wait until sunday night (saturday is wife night)
677 DR Year of Resonant Silence: Gilgeam of Unther sends a naval armada to crush the rebellious Wizards’ Reach. The Untheric fleet suffers terrible losses in a great storm and turns back without landing. 679 DR Year of the Scarlet Sash: Unther recognises the League of Samathar. Unther never recovers from the long, costly campaign to retain the Wizards’ Reach, and the Second Untheric Empire ends. End of the Second Untheric Empire 680 DR Year of the Long March: Chondath mercenary forces begin the long march home after ensuring the collapse of the second Untheric Empire.
I reckon there is a fairly concrete link there between the cessation of the Wizards Coast cities from Unther and the formation of the League of Samathar and the Empire of Unther hiring mercenaries from Chondath to deal with them (a conflict stretching nearly 2 centuries).
For my alternate dimensions project I had a sizable proportion of the mercenaries remain in Chessenta (because of troubles in Chondath) and that is the beginning of how Chessenta became contested territory.
Of course the most obvious link between Chondath and Sembia is that Chondath founded the cities on the Sembian coast and (not sure of the date but probably around 300 DR) and then they gain independence from Chondath in 902 DR.