How would Joseph Smith have guessed about native leaders being incorporated in power structure after subjugation?

The Book of Mormon mentions instances of native leaders being incorporated in power structure after subjugation, such as in Mosiah 19:26-27:

And also Limhi, being the son of the king, having the kingdom conferred upon him by the people, made oath unto the king of the Lamanites that his people should pay tribute unto him, even one half of all they possessed.
And it came to pass that Limhi began to establish the kingdom and to establish peace among his people.

In an analysis of 131 positive correspondences between the Book of Mormon and Dr Michael Coe’s book “The Maya”, Bruce E. Dale and Brian Dale remark:

“Mesoamerican ’empires’ such as Teotihuacan’s were probably not organized along Roman lines; … rather, they were ‘hegemonic,’ in the sense that conquered bureaucracies were largely in place” (p. 100). “it seems obvious that many of the native princes were incorporated into the new power structure” (p. 206). “Or perhaps Calakmul found it easier … to rule through local authorities” (p. 276).
The Book of Mormon and The Maya are both specific and detailed about this practice. As Dr. Coe suggests, the only model Joseph Smith might conceivably have heard about for control of subjugated peoples was the Roman one, which was the opposite of the system used among the Maya, and also the opposite of the system used in the Book of Mormon. How did Joseph Smith “guess” that one correctly? Specific, detailed and unusual.
– Bruce E. Dale and Brian Dale – Joseph Smith: The World’s Greatest Guesser (A Bayesian Statistical Analysis of Positive and Negative Correspondences between the Book of Mormon and The Maya)

Where would Joseph Smith have learned about this practice?

See:

Bruce E. Dale and Brian Dale – Joseph Smith: The World’s Greatest Guesser (A Bayesian Statistical Analysis of Positive and Negative Correspondences between the Book of Mormon and The Maya)

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