So let us look to the Book of Mormon exclusively for the geography of the Land of Promise.
According to the many descriptions of the ancient writers, and using only the language found in the scriptural record of the Book of Mormon regarding the Land of Promise, the following factual statements are undeniably true:
1. The land is divided into two major and basic parts or land masses—The Land Northward and the Land Southward (Alma 22:32; Mormon 2:29).
2. These two land divisions are connected by a “small” (Alma 22:32) and “narrow” neck (Alma 63:5) of land (Alma 22:32) with water on both sides of the neck (Alma 50:34). While that is the description used to describe an “isthmus,” the word “isthmus” is never used in the scriptural record—only neck of land (Ether 10:20).
3. The Land Northward (Ether 10:20) was the home of the Jaredites beginning sometime after the Flood at the time of the Tower of Babel and Confusion of Languages (Ether 1:33). These Jaredites never occupied land south of the narrow neck, a land they reserved as a hunting or animal preserve (Ether 10:21) and went into only to hunt for game.
5. Physically, the narrow neck of land, which was the only connection between the Land Southward and the Land Northward (Alma 22:32), was only the distance in width from sea to sea that could be crossed in a day and a half journey by a Nephite (Alma 22:32),
6. This narrow neck had a narrow “pass” (Alma 50:34; 52:9; Mormon 3:5) or “passage”(Mormon 2:29) running through it by which people could pass through from the Land Southward into the Land Northward and vice versa (Mormon 2:29).
7. This narrow neck and passage was the only land bridge or means of people movement from the Land Southward and the land Northward and was the only thing keeping the Land Southward from being entirely surrounded by water (Alma 22:32).
8. The Land Southward was divided into two parts, called the Land North and the Land South (Alma 46:19; Helaman 6:9). The Land North was also called the Land of Mulek, for the Lord brought Mulek into that part of the Land Southward, and the Land South was called the Land of Lehi, for the Lord brought Lehi into the southern part of the Land Southward (Helaman 6:10).
9. Though not specifically indicated, the Land Northward was also surrounded by water for Jacob tells us the Land of Promise was an island in the midst of the sea (2 Nephi 10:20), which Nephi recorded on the Plates (2 Nephi 11:1), and Mormon abridged Helaman’s remark that the Land of Promise was occupied by the children of Lehi from the Sea South to the Sea North and from the Seat East to the Sea West (Helaman 3:8).
10. Describing the entire Land Southward, Mormon tells us that it was divided in the far south by the Land of First Inheritance (Land of Lehi) for that is where Lehi landed along the west seashore (1 Nephi 22:28),
11. Moving from south to north, the Land Southward contained the Land of Nephi (Alma 22:27,34), that ran from the Sea East to the Sea West, to a narrow strip of Wilderness--sometimes referred to as a line (Alma 50:11), that that ran from the Sea East to the Sea West (Alma 22:27), to the north was the Land of Zarahemla (Alma 22:27), the latter running from the Sea West toward the east, where the borders of the land are along the River Sidon and the Land of Gideon (Alma 8:1, 17:1 is just beyond to the east.
Also to the east of the Land of Zarahemla is the Land of Antionum (Alm 31:3), and to the north of the Land of Zarahemla is an unnamed land (3 Nephi 3:23), and beyond that is the Land of Bountiful, which extends to the narrow neck of land.
12. On the north of the narrow neck of land is the Land of Desolation (Alma 22:30), and along the northern borders of that would be the Jaredite land of Moron (Ether 7:6), where the seat if the kingdom was held for most of the Jaredite period.
13. In a non-descript manner, north of that area is the Land of Many Waters and the Land of Cumorah (Mormon 6:4), and within the latter, the Hill Cumorah (Mormon 6:2), also called by the Jaredites, the Hill Ramah (Ether 15:11), were the demise of both great nations, the Jaredites and Nephites, took place. And to the north of that area are the Waters of Ripliancum.
14. Within the major land areas (i.e., Land of Nephi, Land of Zarahemla) are other subdivisions or “lands,” for each city or settlement had an area of “land” around it, such as the city and land of Manti (Alma 16:6), the city and land of Mulek (Alma 51:26), the city and land of Moroni (Alma 51:22), etc., and in Lamanite lands, the city and land of Ishmael (Alma 17:19), Middoni (Alma 20:4), Jerusalem (Alma 24:1), etc.
15. In terms of elevation, we know that the city of Nephi in the Land of Nephi sits up (Alma 27:23) in a highland valley, surrounded by hills (Mosiah 7:5-6; 11:12) at a considerable elevation since the Lamanites are always coming down (Alma 27:5) to do battle in the Land of Zarahemla, which is located at a lower elevation.
15. Far to the south in the Land of First Inheritance along the West Sea (Alma 22;28), is a large forest big enough for wild beasts and domesticated animals to coexist for quite some time, and where gold, silver and copper are abundant (1 Nephi 18;25);
16. Also in this Land of First Inheritance ; where a climate exists that would allow “seeds of every kind” to grow exceedingly and provide an abundant harvest (1 Nephi 18:24).
While theorist after theorist tries to make the Land of Promise look different than this, this is the way Mormon and others describe it, therefore, it should be understood that this is the way the land was laid out. Any supplemental material used beyond the Book of Mormon itself, must agree with the placements of these lands as described in the scriptural record.