Refugees

The refugees are people fleeing the Fire Nation's persecution during the Hundred Year War. These people had been forced to flee their towns and cities, and have had to make their way to Ba Sing Se, the last free Earth Kingdom capital.

The People
Not all people whose towns were taken over by the Fire Nation left to travel. Haru and the other villagers did not leave their town, but continued to survive after the Earthbender men were imprisoned.

The Mechanist and his son Teo had to leave their town after the Fire Nation destroyed it. They found the Northern Air Temple, and moved in, with The Mechanist altering the Temple to suit their needs, including tearing down walls, and a courtyard for a new bathhouse

However, people like Tahn and Ying, whose home was invaded by the Rough Rhinos had no choice to leave, and set out North, to Ba Sing Se. They hoped to board the Ba Sing Se ferry, however their passports and tickets were stolen, and so Aang led them through the Serpents Pass.