This is the land south of the Lamanite Line of Possession and in general terms is referring to “Lamanite lands” meaning, “Lamanites by birth” or in other words, the lands of pre-existing, neutral in belief people (the Hopewell). How far north they were during Book of Mormon times in this Land Southward is yet to be determined.
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.