You were traveling to the north pole with Avatar Aang And his friends. You were standing in front of the gates of Omashu. Since Aang wanted to visit real bad.

"They don't take kindly to outsiders in Omashu"

A guy who was driving a carriage next to you stated.

Katara ended up making the kind stranger sneak you into the city. And that's how you ended up sitting next to the stranger. While the three others were hiding in the cargo.