The origins of the dispute date back centuries but came to a head last month after Japan nationalized the tiny islands, called Senkaku in Japan, the world's No. 3 economy, and Diaoyu in China, the world's No. 2 economy. The move set off violent protests in at least two dozen Chinese cities. Angry mobs torched a Panasonic factory, looted several Japanese retail outlets and burned Toyota and Honda car dealerships.Learn what the long term effect is here.