In another video I describe what was known to Joseph Smith's contemporaries about the ruins in central, south, and north Aerica.
https://www.youtube.com/watch?v=WJ7Pbn4pTlE&t=5s
Here is part of it:
Singularity of the Mound Builders
Many early writers explicitly linked the North American mounds with the ruins of Mexico, Central America, and Peru. James Sullivan writing in 1795 asserted that the Ohio mounds and fortifications “must have been raised by the people of Mexico and Peru, because the northern nations never possessed the art.” ( James Sullivan, The History of the District of Main (Boston, 1795), 83.) Thaddeus Harris asserted in 1805 that North American burial mounds and fortifications were of “the same structure” of those of the Mexicans. (Thaddeus Mason Harris, The Journal of a Tour into the Territory Northwest of the Alleghany Mountains; Made in the Spring of the Year 1803 (Boston, 1805), 165 66.) Yates and Moulton also saw the ruins of their own state of New York as part of one great project:
In 1824 the Columbian Historian described this chain of ruins in much the same way:"These remains of art may be viewed as connecting links of a great chain, which extends beyond the confines of our state, and becomes more magnificent and curious as we recede from the northern lakes, pass through Ohio into the great vale of the Mississippi, thence to the Gulf of Mexico, through Texas into New Mexico and South America. In this vast range of more than three thousand miles, these monuments of ancient skill gradually become more remarkable for their number, magnitude, and interesting variety, until we are lost in admiration and astonishment." John V[an] N[ess] Yates and Joseph W[hite] Moulton, History of the State of New York (New York, 1824), 19.
Such descriptions of course imply that all structures were engineered by one group—the mound builders. Many writers speculated that this group originated in the north and then migrated south into Mexico and Peru, building greater and greater mounds. Others believed the group originated in the south and was pushed into North America by savage tribes. The fortifications in the Great Lakes region would thus have been a last desperate effort at defense."An observing eye can easily mark in these works, the progress of their authors, from the lakes to the valley of the Mississippi; thence to the Gulf of Mexico, and round it, through Texas, into New Mexico, and into South America; their increased numbers, as they proceeded, are evident; while the articles found in and near these works, show also the progressive improvement of the arts among those who erected them." Columbian Historian, 20 Aug. 1824, 69.
It is not widely known, but in 1842 Caleb Atwater wrote a letter to the postmaster of Nauvoo, who was then Sidney Rigdon, and proposed a special edition of the Book of Mormon to be bound with his 1820 study of the Ohio mounds. In this letter, he made the following interesting statement:
Whatever the theory, the northeastern mounds were prime focal points—either the beginning or the end. Western New York was right in the center as one observer would write in the Ohio Gazetteer in 1819,Great doubts exist as to ... whether they came from Asia across at Behring’s straits, and journeying onwards to Western New York; Then, progressing slowly in a south western direction until they reached Mexico and Peru: or, starting from the last countries, they moved in a north eastern direction to Western New York. Perhaps, your prophet has found the records which they left buried in the earth, which inform us of all the migrations of that ancient people.Caleb Atwater to Postmaster, Nauvoo, IL, 16 Nov. 1842, copy in Stanley Ivins Collection, Utah State Historical Society, Salt Lake City.
This would place significant mound builder history right in Joseph Smith’s backyard.“The place where they commence, or at least, where they are very remarkable, is in the western part of the state of New York, near the southern shores of lake Ontario.” John Kilbourn, The Ohio Gazetteer (6th ed.; Columbus, 1819), 20.