While the initial plan for Magic Kingdom didn’t include Pirates of the Caribbean, that doesn’t mean the park was never going to see anything similar to it.
Disney may have skipped a Pirates attraction thinking guests in the southeast wouldn’t need it, but instead, at one point the plan was to bring a taste of the Western U.
Marc Davis, the same Imagineer who designed the original Pirates of the Caribbean attraction had an idea called the Western River Expedition, which would be a boat ride just like Pirates, but would instead take guests through a version of the wild west.
The ride itself was part of a larger concept called Thunder Mesa Mountain, which would also include a runaway mine train attraction and a log flume ride among other things.