Avatar: The Last Airbender takes place in an Asian-inspired setting where gifted individuals can bend the four elements, with unique cultures and nations centered around each. While the Fire Nation is an innovative and aggressive place like a hungry flame and the Earth Kingdom is stoic and tradition-bound like the earth, the Air Nomad culture is entirely unique.
In previous eras, all Air Nomad members were benders thanks to their strong affinity for spirits. These people were also known for their general pacifistic ways and the blue arrow tattoos on their heads, arms and legs. The arrow tattoos are more than mere war paint, however -- they represent everything that makes an Airbender master what they are.
The Evolution Of Air Nomad Tattoos in Avatar
Ever since the long-lost days of Avatar Wan, Airbenders have been pacifistic, robe-wearing monks who are at peace with spirits and the natural world around them. At the time, those gifted with airbending from their patron lion turtle wore a more primitive version of Air Nomad robes, and most notably, they already had blue forehead tattoos and shaved heads. These early tattoos roughly resembled those seen on later Airbenders such as Aang and his son Tenzin -- except the former ones did not form arrows. They were more like an upside-down T with small dot at the end, and in later generations, this prototype design would undergo some changes.
After humanity parted ways with the lion turtles, human benders turned to other natural benders from which they could learn their craft: badger-moles, dragons, the moon and, in the case of early Airbenders, the sky bison. Avatar Aang had knowledge of the sky bisons' early role in teaching humans to bend air, but not that of the lion turtles -- that trivia was lost to time, which explains the lion turtle retcon in The Legend of Korra.
What Aang doesn't know is that these ancient Airbenders eventually modified their forehead tattoo design to mimic the arrow pattern found on sky bison fur, to pay tribute to their new airbending teachers and symbolize the newfound bond between them. By Aang's time, it was a firmly established tradition for young Air Nomads to become bonded to a single sky bison each -- with Appa being Aang's own partner -- so naturally, Air Nomads had forehead tattoos to match.
The Modern Meaning Of Air Nomad Tattoos in Avatar
By Aang's era, the forehead tattoos had taken on a great deal of meaning among the Air Nomads and could also be found on the benders' arms and legs. These tattoos are not given to every member of the Air Nomads -- only to a bender who has demonstrated sufficient skill, marking them as a true Airbender master. In particular, an Airbender must achieve full mastery of all 36 tiers of airbending forms to receive these tattoos, a serious challenge that takes many years to complete.
Another way to earn these tattoos is for an Air Nomad to single-handedly invent an all-new airbending technique, regardless of how many tiers of training that bender has already completed. Aang, for example, earned his tattoos at age 12 when he invented the air scooter. Two generations later, his granddaughter Jinora earned her own tattoos at age 11, which is unusually young for the Air Nomads. This speaks to Jinora's enormous natural talent and skill as an Airbender.
Air Nomad tattoos are almost entirely symbolic, having few other physical functions outside of a regular one, and they are presumably made through traditional methods. There is one exception: as Aang demonstrated many times in Avatar: The Last Airbender, Air Nomad tattoos will all glow with white energy when the Avatar State is activated, shining with the light of the spirit Raava. All Avatars' eyes glow when they enter this state, but Air Nomads alone have glowing tattoos to match, making for quite a visual. This doesn't add to the bender's actual power, but it may be an intimidating sight for the Avatar's enemies all the same.
