North America is geographically the bit north of the Panama isthmus. In practice a "Central American" region is normally accepted, which pushes the southern limit of "North" America further north. To the north it pretty much extends to the Arctic ice-cap (although politically the Canadians and the Inuit have their respective claims in addition to that of the United States of America).
In period, North America was inhabited by native settlers (who appear to have crossed the Bering Strait at some pre-period point), by travelling parties of polar dwellers, in the extreme north and north-west), and by European colonists (no-one has successfully argued the case for naval colonisation across the Pacific).
Variously the first European contact is said to have been by Vikings (qv Vinland), by St.Brendan, by Amerigo Vespucci (on behalf of Italian interests) or by Christopher Columbus (on behalf of the Portuguese Crown. Certain other theories also argue that the last of the Knights Templar journeyed there, after the suppression of their order by the King of France.
Most Society personae of a North American sort will have to be European colonists, pending the verification of authentic records of the pre-colonial indigent culture. These will generally be of Spanish, English, Scots or French origin, as Portugal tended to concentrate on the Southern American sub-continent.