Complex sentence: Tanasi appears on multiple maps of the Overhill territory in the 1720s and 1730s, but Chota doesn't, which suggests that Chota may have been part of Tanasi, or may not have been considered a town before the 1740s.
Split into simpler sentences: Tanasi appears on multiple maps of the Overhill territory produced in the 1720s and 1730s, but Chota does not. This suggests that Chota may have been part of Tanasi, or may not have been considered a town before the 1740s.