The Avatar was one with unmatchable power,someone who could enslave entire villages in merly days.He was feared across demesions so much that people began to hunt each and every one down to kill them off.They thought they succeeded when it was 100 years without one but little did they know Avatar Aang wanted them to believe that when he sealed him,Momo,and Aapa off in an iceberg for hundred years so they could use their idea of the idea of the Avatar ever ending against them.