Maztica

Maztica is one of the three off-shoot campaign settings to Forgotten Realms, alongside Kara-Tur and Al-Qadim. Like its counterparts, it focuses on an "ethnically different" area of the Toril world - in this specific case, a Mesoamerica expy, in contrast to the Arabian Niiights Al-Qadim and the "Oriental" Kara-Tur. With a touch of Inca.

Noted for being pretty well researched, for the time... because it shamelessly ripped wholesale from the actual history of Terminal Post Classic Mesomerica. This, complete with the invasion of Conquistador-expies (a Helm-worshipping legion of mercenaries) who commit such brutal atrocities against the natives that Helm has to found a whole new Paladin order to try and make up for the shit they did.

After Tomb of Annihilation was released, Maztica became legal to post content for on the DM's Guild. A fan group has made a huge translation of the setting to Dungeons & Dragons 5th Edition... as to whether it manages to be something more than "Messicans ported wholesale to the Realms", well...

AD&D

Maztica made its debut in the ere of Advanced Dungeons & Dragons 2nd edition, first appearing as a novel trilogy before being converted into a setting with the Maztica Boxed Set.

We'd tell you the lore but if you've read William Prestcott's The History of the Conquest of Mexico, you know it already. Seriously. The main difference is that after Cortesthe Amnites shows up, the Not Aztecs get transformed into monsters by MAGIC.

This box was followed by three further publications: FMA1: Fires of Zatal, a basic setting-introducing adventure; FMA2: Endless Armies, an adventure in which Maztican or explorer PCs try to stop a plague of giant ants that is devastating the jungle, and FMQ1: City of Gold, a campaign expansion that details the more Incan-flavored northern reaches of Maztica.

Ed Greenwood didn't write any of this shit and he didn't like that it got tagged into his Realms. He has always asserted that he felt it and the other more Historical Fantasy focused Realms subsettings of Kara-tur and the Hordelands were a bad idea that took away from the fundamental fantastical feel of the Realms, led to problems at the table when you got That Guy yammering on about "historical inaccuracies" in a game that wasn't supposed to be real-world history in the first place, and was just generally a bad idea. Given the reception to such sub-settings in the modern era, ol' Greenwood hit the nail on the head with prophetic accuracy.

3e

Maztica continued to exist in Dungeons & Dragons 3rd Edition, but that's about all that can be said of it. Not fitting into any of the "regional" splatbooks like Unapproachable East or Shining South that were reinvented in this edition, it essentially just got mentioned in the campaign guide and was then not touched. Muh Cultral Propiation wasn't (yet) the issue it would become in the Wokening of 2013 on, but even then, this setting wasn't in the best odor around here.

There was an adaptation of Pluma and Hishna magic in Dragon Magazine #315.

4e

Maztica actually vanished from the face of the Forgotten Realms due to the Spellplague when the setting was updated to Dungeons & Dragons 4th Edition. Nobody actually knows why the designers did this; some theorize they wanted to just excise one of the more embarrassing and often-cited as racist regions from the game... ironically, this has led to WotC being called racist because it was generally the "non-White" portions of Faerun that got most heavily tweaked into overtly fantastical cultures. But then, you really can't win with those people, can you?

5e

Maztica was officially restored to the Forgotten Realms in Dungeons & Dragons 5th Edition, with the semi-neighboring continent of Chult starring as the setting of the adventure module Tomb of Annihilation. But WotC theselves haven't done anything with it yet... instead, a bunch of total madlads have taken advantage of the DM's Guild to push forth their unofficial 5e translation, which is... well, to call it a labor of love is an understatement!

The "Maztica Returned" project has been ongoing for years, and is massive in scale, with meticulously researched lore on both the Realms side and the real-world side, with a determined focus on promoting native Maztican PCs and generally altering the feel to be less rooted in history and more in fantasy. To sum up, they've come a long way to fixing this lazily- designed, barely-playable dog's breakfast of a setting.

These same madlads went so far as to expand Maztica to create its own subsetting; Anchorome.