The Avatar universe is very complex, vast, and mysterious. There's so much known and unknown about the show, down to the minor details to major events that fail to explain. My theory on the show is that during the time of Avatar Wan, and Avatar Aang, the world suffered an unknown apocalyptic event that has forced man to start over. In this will be evidence as of support to this theory.
This theory is basically as the title says: That the avatar series suffered an apocolypse before the series began. Now I know it may not seem likely at first, But aspects in the show say otherwise...
In the show, there is plenty of past events that occurred before either Avatar: The Last Airbender or Legend of Korra ever occurred. These include Wan shi tong raising his library to the physical world, Tui and la turning into koi fish for the Northern water tribe, and when Raava connected the spirit and human worlds together. What's wrong here is when this occurred.
- In the episode Beginnings, Part 1 and Part 2, it shows the time of the character Avatar wan and how he became the first avatar when Korra lost her memory. One of these scenes shown was a Chinese palace of the Chou estate, where Wan stole food from the Chou brothers.
...there is a major problem here. If you think about the development time it took between A:TLA and TLOK, it only takes 70 years to build Republic City, which is suppose to resemble a advanced city, from the plans and cars in it as well compared to the rest of the world...But when they show Avatar Wan's time, it is remarkably similar to Avatar Aang's time. The resemblances include:
- spiritual resemblances
The catch though is that avatar wan lived 10,000 years ago prior to Avatar Korra. If it only takes seventy years for man to turn Yue Bay into Republic City after the 100 year war, then why after 9,930 years after avatar wan, does nothing change until past Avatar Aang's time? If the timeline was correct, and avatar wan did live such a long time ago, then this means that his people should still be caveman, living in the forest, instead of the status as shown in the episode.
Now if you do look at the History of the show, there's a gigantic time gap between Avatar wan, and Avatar Aang. Sure there's information on what happened, but none of it was shown. In fact the farthest past shown aside from the first avatar incident was in Avatar Kyoshi's time, when she founded kyoshi island. A lot of other things could of happened then that can easily be missed, or simply forgotten after so long. even from Wan Shi Tong's famous library.
One thing that supports this apocalyptic theory are the animals. Almost all animals in the show are either based off legends (such as Unagi, Fang, or the Lion turtle), or a type of animal called chimeras. Chimeras are the main group of animals that are basically hybridized. All sorta of examples are shown, a few include Sky Bison, Buzzard-Wasp, Cat-deer, or Hippo cow. Animals like this simply can't be from any natural selection of any sort, no matter what habitat or climate an animals in. Perhaps the Apocolyptic event forced these radioactive, sci-fi changes in animals, resulting in the fauna in the show.
While it is aware that hybrid animals are shown during Avatar Wan's time (mainly Hybrid pigs). And while normally this would debunk the whole thing, consider this: If you look, there is evidence of hybrid pigs in the real world, Examples evident in that episode, mainly the cow pig and sheep pig are example of real life hybrids. (in case you don't believe that, here's an example of a real life hybrid pig: http://i.dailymail.co.uk/i/pix/2010/04/16/article-0-092820F8000005DC-314_634x423.jpg)
So in case you still dont understand, the hybrid pigs here dont count since their examples of real animal hybrids instead of sci-fi examples like the others shown.
In the show, there is normal animals, but are altered in some way. Examples include giant beetles in the desert, and huge koi fish off the coasts of kyoshi island. These animals aren't chimeric, but they are still mutants compared to their regular counterparts, signs that something must of happened to make them this way.
In the show, there were evidence of regular animals, no mutations present, but the show put it that they were either rare or non-existent. A perfect example is the Earth king's pet bear named Bosco. In his backstory, he was described as the only known species of normal bear, and a bunch of zoologists were sent out to find Bosco a mate, no evidence was said upon the success/failure of the mission. This signifies that 90% of all regular animals were mutated in some way somehow. There are other minor examples which include pets, fish, rodents, birds, and insects. This says that most small animals avoided any mutations, exceptions included the Winged-Lemur.
Throughout the 1st series, there's many evidence of ancient buildings and ruins shown. Examples include the ruins of Taku (shown above), and the Sun Warriors' ancient city. These ancient cities Oddly resemble those that were current among Avatar Aang's time, further evidence that there was a advanced time before Aang existed. The perfect example of this is the sun worrier's ancient city, which mirrored the fire sage temples surprisingly well.
Special examples include the vehicles seen throughout the show. A important example is the submarines used during the day of black sun. This alone is a rather huge change to the avatar world, giving the fact they still relied mostly on carriages to get around.
Korra's time also had some good examples, in particular the mecha tanks shown. Given the fact they were just inventing cars, how did they get the mind power to know how to make a robot suit? Perhaps they are just re building what once was before apocalypse occurred.
Now before I continue onto Benders, let me say that I am aware that their are other explanations aside from the apocalyptic event that gave benders their powers, but keep in mind that these a pure legends made by people over many years, and legends can easily be proven false as they can be proven real. With that said, let's continue.
In the show, there are 4 distinct elemental powers shown. There's Firebending, Waterbending, Earthbending and Airbending. In the show they had their own "excuses" as to how humans earned these abilities. In Legend of korra, it turns out lion turtles were giving these powers to Avatar wan and his kin during their time. As this might explain the bending back with avatar wan, a power given to an individual doesn't get passed down through teaching. So when the lion turtle's gave up giving powers away, the bending died down. Perhaps this same apocalyptic event had mutated the humans as well, giving them similar bending abilities.
This would also explain the side-abilities (examples including Metalbending, Lightning generation, and other unorthodox bending abilities. While lion turtles explain the main 4, Lion turtles can't give benders these types of Bending styles, meaning that the humans had to cope with these powerful mutations put upon them.
Other evidence are the characters themselves. Shown in ATLA, there are a few characters that simply just can't be without special intervention. Examples are shown below:
In book 3, there is a nameless character simply known as the Combustion man, a nickname given to him by team avatar. Compared to most other people, he is both mysterious and threatening. His own appearance is very unique, even for the avatar world. His various parts, which include a "third eye" on his forehead, a metallic arm and metallic leg. Compared to other firebenders, none of them can match his ability, saying that some sort of mutation happened to him, or "experimental Technique" as it states in his trivia.
In the end of Book 2, a character named Pathik appears. Whats interesting on him is that he has survived far beyond normal human age, precisely 150 years. This makes him the oldest living human in the show, as it states he survived through meditation. However, Meditation and it effects have been known to help you live longer, but not to Pathik's extent of 150. So there has to be another mean as to how he lived so long...
There were many references in terms of knowledge in the show. One reference is the solar eclipse.
In the episode The Library, Sokka and Aang try to discover when the next solar eclipse will occur using Wan Shi Tong's planetarium machine. This alone is a rather advanced reference to the time frame. Most primitive people had their own stories behind how eclipses occur, but in the show, it almost seemed that they fully understood that the moon covered the sun during this instead of usual legends.
In the episode The Day of Black Sun, Part 1: The Invasion, it seems that the reference of space is old news. After Aang explains how he can't use his avatar state, Toph, bored, goes on about it being "something about space". Although this is rather small, it does say that the people are already aware of space to an extent.
They are also aware of the moon's effect on the water, as said when Team Avatar was in the North Pole.
This type of knowledge says that they had learned this stuff before their current time. Evidence of advanced knowledge before the series began.