Book of Mormon lands were small (1.5 days wide, Alma 22:32), that’s why serious researchers accept the Limited Geography approach. Simply put, if final battles occurred in Palmyra, New York around the Hill Cumorah, then that’s where Book of Mormon lands are.
In fulfillment of Book of Mormon prophecy, Book of Mormon lands were purchased by white Gentiles “for their inheritance” (1 Nephi 13:15) with the Phelps and Gorham Purchase.
The core area inhabited by the Nephites matches the same area of the Holland Land Purchase. Book of Mormon lands do compare to the size of Bible lands:
See also: Error #13 – Distances
In these small areas, warfare occurred numbering in the millions:
In all Israel there were one million one hundred thousand men who could handle a sword, including four hundred and seventy thousand in Judah. (1 Chronicles 21:5, NIV)
He saw that there had been slain by the sword already nearly two millions of his people, and he began to sorrow in his heart; yea, there had been slain two millions of mighty men, and also their wives and their children. (Ether 15:2)
Where are the bones in Israel? The same place as the bones around Cumorah:
Their flesh, and bones, and blood lay upon the face of the earth, being left by the hands of those who slew them to molder upon the land, and to crumble and to return to their mother earth. (Mormon 6:15)
Where are the evidences of large populations?
The Israelites journeyed from Rameses to Succoth. There were about six hundred thousand men on foot, besides women and children. (Exodus 12:37)
So the Lord sent a plague on Israel, and seventy thousand men of Israel fell dead. (1 Chronicles 21:14)
He conscripted seventy thousand men as carriers and eighty thousand as stonecutters in the hills and thirty-six hundred as foremen over them. (2 Chronicles 2:2)
Then the angel of the Lord went out and put to death a hundred and eighty-five thousand men in the Assyrian camp. When the people got up the next morning–there were all the dead bodies! (Isaiah 37:36)
And King Solomon offered a sacrifice of twenty-two thousand head of cattle and a hundred and twenty thousand sheep and goats. So the king and all the people dedicated the temple of God. (2 Chronicles 7:5)
In one day Pekah son of Remaliah killed a hundred and twenty thousand soldiers in Judah–because Judah had forsaken the Lord, the God of their fathers. (2 Chronicles 28:6)
But Nineveh has more than a hundred and twenty thousand people who cannot tell their right hand from their left, and many cattle as well. (Jonah 4:11)
“They (North American Indians) once numbered 16,000,000 and daily sent that number of prayers to the Almighty or Great Spirit in thanks for his goodness and protection. Their country was entered by white men, but a few hundred years since: and 30,000,000 of these white people are now scuffling for the goods and luxuries of life, over the bones and ashes of 12,000,000 of red men: 6,000,000 of whom have fallen victims to the small-pox, and the remainder to the sword, the bayonet, and whisky: all of which means of death and destruction have been introduced and visited upon them by acquisitive white men:” (Geo. Catlin, Illustrations of the Manners, Customs, and Condition of the North American Indians, with Letters and Notes, Written During Eight Years of Travel and Adventure Among the Wildest and Most Remarkable Tribes Now Existing, vol. 1, tenth edition, 1866, p. 6)
Where is all the gold?
I have taken great pains to provide for the temple of the Lord a hundred thousand talents of gold, a million talents of silver, quantities of bronze and iron too great to be weighed (1 Chronicles 22:14, NIV)
And it came to pass that king Noah built many elegant and spacious buildings; and he ornamented them with fine work of wood, and of all manner of precious things, of gold, and of silver, and of iron, and of brass, and of ziff, and of copper (Mosiah 11:8)
When compared to the Bible, the Book of Mormon is solid.