The Nephites had driven the "Lamanites" toward "the east by the seashore" according to Alma 22:29. Apparently this statement might be inferring that in driving these "idle" Lamanites toward the east coast, the Nephites had cleared or extended the eastern part of the land of Bountiful also. The Nephite thinking at this time might have been that to have somewhat "idle" Lamanites on their west coast and "driven" Lamanites on their east coast did not endanger them; in fact, it kept trade routes somewhat "neutral." However militarily and politically the Nephites now felt that they had "hemmed in the Lamanites on the south". This theory would be tested to the maximum in the years to come. In fact, chief captain Moroni would ultimately have to put up a defense line to seal off both the west coast travel corridor and the east coast travel corridor. (Alma 50:32-34; 51:28-32; 52:9; Helaman 1:23,28; 4:6-7)
Mormon does not say here that the land of Bountiful definitely reached the east sea, only that it stretched "from the east unto the west sea." Nevertheless, as far as the eastern part of Bountiful ultimately reaching the east coast, we find in Alma 51:32 that "they (the Nephites) did slay them (the Lamanites) even until it was dark. And it came to pass that Teancum and his men did pitch their tents in the borders of the land Bountiful; and Amalickiah did pitch his tents in the borders on the beach by the seashore." This places the borders of the land Bountiful very close to the eastern seashore. Also, we find a similar scenario in Alma 52:18---53:3. Therefore, we can probably say that the borders of the land Bountiful were very close to if not right at the east sea. [Alan C. Miner, Personal Notes]