When John Lloyd Stephens and his party arrived in the Yucatan in 1840, the peninsula was not exactly in rebellion, but had declared itself the autonomous Republic of Yucatan. Negotiations with the central Mexican government were ongoing. As a defensive measure, the Republic of Yucatan had entered a military alliance with the Republic of Texas. Texas naval vessels were patrolling the Gulf of Mexico.
It all sounds like something from an alternate history novel. It's a glimpse of a dead end of history, a contingent path that went nowhere. Every American is taught about the Republic of Texas (the Alamo, remember?), but as a prelude to the 1846 Mexican War, and as part of the path to the Civil War. Not for it's own sake (not outside of Texas, at least). But it was, for a short time, an existing entity, a state with ambassadors and treaties and the like. As was the Republic of Yucatan. As were any number of vanished corners of history. It's an odd thing to read about.
One great value of old travel books is their firsthand encounters with these nooks and crannies of the world that were not in the middle of the action. John Kirk Townsend in the Sandwich Islands, Mungo Park on the banks of the Niger, Darwin in Argentina and Chile. Almost no one thinks to read The Voyage of 'The Beagle' for his description of Argentina and the gauchos in the 1830s. But it's there, and it's worth the time, and where else can you read about them?*
* I know, Domingo Faustino Sarmiento's Facundo (1845). Is that a book for non-specialists? We shall see.