This is the land south of the Lamanite Line of Possession and, in general terms, referring to “Lamanite lands,” meaning “Lamanites by birth” or, in other words, the lands of pre-existing, neutral in belief people (the Hopewell).
At its furthest point south is where Lehi’s ship docked in Erie, PA, at a natural harbor called Presque Isle Bay. Nephi’s group (the righteous) fled north a far distance to escape his wicked brothers and their wicked wives (mother Sariah stayed with them). Within the general land called Nephi is a sub-area called Land of Nephi, which surrounded the city Nephi founded.