Long before the French erected a fort at Beauséjour, Acadians established themselves in the Chignecto region, which they called Beaubassin. The earliest settlers arrived in 1672-1674, relocating there from Port-Royal. This was the first of several voluntary out-migrations of Acadians from the Port-Royal area. Similar movements began in the 1680s for the Minas Basin area - Grand-Pré, Pisiquid and environs - and in 1686 for Cobequid. At Beaubassin, as in other areas, the Acadians dyked and farmed large tracts of marshland.

In 1676, Michel Le Neuf de la Vallière received a seigneurial grant in the Beaubassin region and established himself on a height of land not far from Beauséjour, known as Île de la Vallière (later Tonge's Island). As of 1686, there were more than 22 Acadian farms on the two ridges where 65 years later Forts Beauséjour and Lawrence would be erected.