Lots about the Spirit World has remained an Avatar mystery for years, but a closer look at Korra and the books provides some interesting answers.

The Spirit World is one of the most important parts of Avatar: The Last Airbender, but the details of what it is and how it works can be difficult to nail down. The Legend of Korra provides a lot of extra explanation on the nature of the Sprit World and how it relates to the physical world, and it’s necessary to look at this added lore in combination with the Spirit World’s portrayal in Avatar: The Last Airbender to develop a clear understanding of how exactly it all fits together.

The first mention of the Spirit World comes very early in Avatar: The Last Airbender, in only its seventh episode, where Aang, Sokka and Katara come across an Earth Kingdom village that is being attacked nightly by a monstrous spirit named Hei Bai. This is the first time the show defines the Avatar as “the bridge” between the mortal world and the spirit world. Over the course of the two-part story, Aang makes his first journey into the spirit world, meets his past life Roku, and learns the basics of the Avatar’s role as the spirit bridge.

Aang visits the Spirit World a handful of times over the rest of the show, usually to communicate with Roku, but occasionally to seek out additional spiritual wisdom, like when he visits Koh the Face Stealer to learn about the moon and ocean spirits. This particular voyage is momentous because it’s the first time Avatar shows the Spirit World as a separate place, with its own unique flora, fauna, and geography. Prior to this point, Aang’s experience with the Spirit World is only as a spirit in the physical world, as he has not yet learned how to enter the realm itself directly through meditation.

This idea of the Spirit World as a parallel, alien plane of existence is expounded on significantly in The Legend of Korra, particular in season 2, when the history of both worlds, how they are connected, and their ties to the Avatar are explained. So how does it all work?

The Spirit World's History & Realms Explained

In the two-part Legend of Korra episode “Beginnings,” the world is shown as it was before the Avatar existed. Spirits roam the physical world freely in untamed regions known as the “Spirit Wilds,” while humans take refuge in cities built on the backs of Lion Turtles. Travel between the physical and spiritual realms is possible through the two spirit portals – one of which exists at the North Pole, the other at the South.

While the exact timeline of when the portals were created and when spirits first entered the physical world is unknown, there are a few hints throughout the shows. During the siege of the North Pole, Roku tells Aang that Tui and La – the moon and ocean spirits – passed over from the spirit world to the mortal world “very near the beginning.” It’s for this very reason that Aang must confront Koh to learn the spirits’ identities, as Koh is the only spirit Roku knows of who is “old enough to remember.”

It’s also significant that Tui and La passed over into permanent, mortal forms as the koi fish in the Spirit Oasis, while the wild spirits shown in “Beginnings” still exist in their spiritual form. Because the portals are what allows for a direct, physical transition between the realms, and because the creation of the moon and ocean would have been major forces in the early days of the physical world, it’s reasonable to assume that Tui and La passed over before the portals existed. So a general timeline in Avatar: The Last Airbender would be: Spirits exist in the Spirit World, then some spirits transition into mortal forms in the physical world, and eventually the portals are opened, allowing for spirits to freely enter the physical world.

As for the actual geography of the Spirit World, that’s a bit trickier. While there are specific locations and landmarks that seem to be consistent across time – such as the Fog of Lost Souls, Xia Bao’s Grove, the Lair of Koh, Hai-Riyo Peak, and the Tree of Time – there’s no real consistency in their physical relationship to one another. As Iroh explains to Korra in season 2, the Spirit World is powerfully affected by personal energy. The weather, time of day, and even the physical nature of the realm can change in an instant based on the present energy. Likewise, there is no concrete distance or orientation between places. Characters seem to cross huge swathes of the realm in very short amounts of time, but this is more because of their intentions and energy than their physical proximity. Put more simply, the Spirit World sends you where it wants you to go, which may also be where you want to go.

Who The People Are In The Spirit World

The primary denizens of the Spirit World are, of course, spirits. Avatar makes it clear thoughout that not all spirits are created equal. Roku establishes at the end of season 1 of Avatar: The last Airbender that different spirits are different ages, though the way a spirit comes into being is never fully explored. In the graphic novel The Search, Aang meets an ancient spirit called the Mother of Faces, who is the creator of every face for both spiritual and mortal beings, and the mother of Koh. The presence of a face can then be used as a sort of marker to age spirits. For instance, because Raava and Vaatu have no faces of their own, they likely preceded the Mother of Faces.

It’s also shown that human spirits can transition into the Spirit World upon their death, as happens with Iroh. This is not the same as an afterlife in Avatar, as not all humans transition into spirits when they die. Only humans who have achieved a powerful spiritual connection are even able to visit the Spirit World, and residing there permanently is another matter entirely. Members of the Red Lotus are able to meditate into the Spirit World and visit Xia Bao’s Grove, for instance, but that does not necessarily mean that they could transition as Iroh does. The specifics of Iroh becoming a spirit are unknown, though his powerful spiritual affinity is shown multiple times in Avatar: The Last Airbender, like when he is able to see the spirits of Roku and his dragon flying over him, when Zhao mentions rumors of Iroh venturing into the Spirit World, and how Iroh is able to sense when the solar eclipse is coming.

Other human spirits exist in the Spirit World in different ways. The Fog of Lost Souls serves as a prison for human intruders, for instance, while the spirits of the different Avatars are tethered to the Spirit World through their connection to Raava. It is commonly believed that when Raava was destroyed and reborn with Korra during Harmonic Convergence, the spirits of Aang and Korra’s other past lives were permanently erased. However, this is never proven. It’s very likely that Aang, Roku, Kyoshi and the other Avatars continue to exist independently in the Spirit World given their own connections to the realm, and that it was simply their direct connection to Raava that was severed.

How Accessing The Spirit World Works

As mentioned above, there are two ways to move between the realms. The first is to move directly from one to the other, which maintains the traveler’s initial form (humans can have their bending and physical bodies in the spirit world, spirits can maintain their spiritual forms in the mortal world). The other way is to transition by shifting between a physical and spiritual form (humans meditating their spirits into the Spirit World, spirits taking mortal forms).

The only reliable way of travelling directly is by using the spirit portals. In The Rise of Kyoshi and The Shadow of Kyoshi, it is revealed that incredibly powerful spirits are also capable of tearing physical rips between the realms that allow for direct transition, as Father Glowworm does. This is likely the result of a concentrated focus of incredibly powerful spiritual energy, similar to the spirit cannon blast that creates the third portal in Republic City.

As for the second kind of travel, methods are varied. Meditation is the primary way humans can move into the Spirit World, and certain locations in the physical world are particular strong in spiritual energy and allow for an easier transition. These include the Spirit Oasis, the Forgetful Valley, and certain sacred areas of the Air Temples.

Specific physical locations can also have powerful ties to certain spirits. For instance, Aang is able to easily access Roku’s spirit at the Fire Sages’ temple, and on his home island – two places where his spirit is still strongly tethered. Since there is little spiritual significance to Roku’s island other than his own connection to it, it’s likely that Aang’s quick move into the spirit realm from there was directly connected to Roku, and amplified by the solstice. In other words, Roku pulled Aang into the Spirit World from a location where his spirit was strong, using the power of the solstice. This can also explain how a spirit like Hei Bai can transition between the Spirit World and a particular location in the physical world without the use of a portal. In Hei Bai’s case, the Winter Solstice combined with Hei Bai’s connection to the forest to allow for easy movement between realms.

How The Spirit World Is Different In Avatar & Korra

For the most part, The Legend of Korra simply builds on the foundation laid by Avatar: The Last Airbender. Korra expands the history of the spirit world and shows a greater range in the kinds of spirits that exist. It also offers more direct explanation as to how the two realms are connected. By the end of The Legend of Korra, physical travel between the realms is once again possible, including from the highly-accessible Republic City portal – which leads to some conflict in the Korra graphic novels.

The main change made in The Legend of Korra is in the spirit world’s connection to bending. In Avatar: The Last Airbender, people believed that bending was learned from various forces in the natural world (the moon, the dragons, the sky bison, and the badger moles). However, Korra makes the lion turtles the original source of bending. Ultimately though, this change fits with Avatar’s original bending lore. Since bending itself seems to be genetically-related, it wouldn’t make sense that a human could develop the skill simply by watching another creature. However, it remains true that the art of bending was learned from the aforementioned natural forces. Lion turtles may have granted the ability to control the elements, but Wan became the first true bender when he learned the techniques of the dragons and others.

The lion turtles themselves remain a mystery. While their faces suggest they are younger than Raava and Vaatu, Raava refers to a lion turtle as “Ancient One” in “Beginnings.” Some fans believe this line is simply a sign of respect, and that the lion turtles are just very old animals. A now-deleted Avatar encyclopedia entry from Nick.com confirmed this, saying that most lion turtles were hunted and killed. However, it’s unclear if this is canon in a post-Korra world. For now, the energy-bending behemoths will remain another one of Avatar’s spiritual mysteries.

Next: Why Legend of Korra Season 5 Never Happened (Was It Canceled?)