I'm rather confused as in which forum should I put this thread, so I put this here. The Mods are free to move this thread everywhere as they please, though.
This is a question that I've asked on other forums but still can't find a satisfying answer, so I hope people of Avatarspirit.net can help me out.

In this scenario, about 80,000 humans, most of them are entire families, couples, etc, are harvested from our world (including Teotihuacan Mayans, Jin/Wei Chinese, Gupta Indians, Sassanid Persians, Byzantine Romans, Franks, Visigoths, Ostrogoths, and Vandals) around 500 AD by a set of harvested vessels and transplanted onto an Earth-like planet several hundred light years away, as part of an experiment in the impact of elemental bending on civilization. In transit they are given immunizations (as well as a few general health clean ups that would extend their lives to about 100 years on average) and they have installed upon their minds two general memory templates via a cybernetic interface. Once they arrive on the planet they are deposited into one of four settlement clusters, each with 20,000 people (which I'll call Pyros, Terra, Aqua, and Aeris for sake of simplicity). Each settlement cluster has a central city that will be home to 5,000 people, 10 towns each with 500 people, and a large number of farms and some mines and similar over an area about 50 km across, all of them are connected with each other by Roman-style road networks. Each settlement has Earth's crops and livestocks as well as early medieval agricultural equipments and weapons. All four societies have access to a decent initial investment of supplies to see them through their first harvests with a good margin of error and are situated in a resource-rich area.
Among the programming the settlers receive is an artificial language (which exists alongside their previous language) distinct to each settlement cluster, as well as images of them being whisked away from Earth by angelic beings to a new home to have Dominion over and to go forth and multiply across. They also have been granted universal literacy in both the Latin and Mandarin alphabets and numerals. Each settlement cluster is located on one of the planet's seven continents on four different sides of the planet, located as Pyros-Terra-Aqua-Aeris, in that order (Pyros and Aqua are on opposite sides of the planet, as are Terra and Aeris, while Pyros is equally far from both Terra and Aeris). Both Pyros and Aqua have the ocean at about 14 km from the central city (with one of the towns being a fishing village), while Terra and Aeris are a thousand kilometers inland at the foothills of a mountain range with vast fertile grasslands between them and the sea. Most importantly, all settlers have been granted distinct elemental bending powers as in Avatar: The Last Airbender and The Legend of Korra.
Pyros - Firebending
Terra - Earthbending
Aqua - Waterbending
Aeris - Airbending
Each settlement cluster has some bending scrolls of their respective elements (see below) scattered on some places. They also come with fireproof and water-resistant books. Each of the four settlements have different versions with some differences but their function is basically identical: as something of a holy text explaining in brief how these people were given divine powers and taken by a benevolent deity from Earth to this new world to call as their own. They also have a warning in their final chapter: that says that while they, the virtuous, were taken to this new world by a benevolent deity, said deity has a malevolent counterpart which did the same with the wicked while giving them corrupt powers to blight this world and that it is their holy duty to purify this world of their corruption. Each civilization will grow and expand before it inevitably comes into conflict with each other.
On the genetics, it works like these:
X-bending + X-bending (parents) = 100% X-bending children
X-bending + Y-bending (parents) = 100% nonbending children
X-bending + nonbending (parents) = 50% X-bending, 50% nonbending children
Nonbending + nonbending (parents) = 100% nonbending children
(I put the genetic stuff above mainly to stop people from asking question about interbending marriage.

And to discourage the four cultures from simply merge with each other)
Specialized bending forms such as bloodbending, metalbending, lightningbending, flight, etc, are indeed accessible for them, once they have unlocked the techniques themselves.
Which civilization and which element will prevail in the end?
