The next stop on the group’s trip is the Earth Kingdom city of Omashu. There, Aang shows Katara and Sokka the Omashu mail delivery system, a massive network of stone causeways which he and his friend Bumi (note: a Sanskrit word meaning ‘Earth’) had once ridden for fun a hundred years previous. The trio gives the chutes a try but runs into trouble after it destroys a cabbage merchant’s cart. Brought before the king of the city, an elderly and erratic old man of substantial skill and strength in earthbending, the three are unexpectedly given a feast, during which the king outs Aang as being the Avatar. He imprisons the three and puts Aang through three deadly challenges the next day to test his skills and earn their freedom, culminating in a duel with the king himself. After Aang passes all of the challenges, the king forces Aang to guess his name. Aang ponders the question, finally deducing the king is his old friend Bumi. Bumi and Aang finally reunite, Katara and Sokka are set free, and Bumi divulges that he put Aang through the challenges as a means of preparing him for his eventual confrontation with Fire Lord Ozai.