The Diaoyu Islands play a big role in fishing land, shipping ports and possible oil deposits to Japan.
Japan had spent about 10 years surveying these 8 Islands; then, on January 14th 1895, claimed them as their own Diaoyu Islands. This had never been a problem with China until the issue of unclaimed oil resources found in the area arose. After the islands gained value to the Chinese government, they began to claim that the Diaoyu Islands had been a Chinese territory since the ancient times as a fishing ground. And yet, years back, when Japan claimed the islands as their territory, China said nothing and stayed quiet until the area showed signs of oil.
It appears that the Chinese are only interested now because of the monetary advantages the Diaoyu islands hold. The Japanese had the land previously claimed under their name and now it is being purloined simply because of the oil value the Diaoyu islands possess. I believe that there is no way that the Chinese just forgot about this little piece of land they supposedly always owned; it seems that they are using ancient history to justify their attempt to swipe resources from their neighboring country, Japan.
