China's old maps showed a China that is much bigger than what it is today. In the old maps, South Tibet, the Indians called Arunachal Pradesh, was clearly a part of China. The map the Indians are using, is a map drawn by an English clerk sitting in London who drew a line claiming that Southern Tibet belonged to the British Empire. And Indians think this is an authority to claim South Tibet as part of India when India did not even exist then.
Old Chinese maps also showed the Ryukyu Island chain was an independent state, not part of Japan. The Japanese only have administrative rights over the islands passed on to them by the treacherous and untrustworthy Americans. Old Chinese maps, especially in the time of the Ming Dynasty, showed most of the islands in the South China Sea belonged to China. The islands of the Philippines then were non states, occupied by hill and fishing tribes.
China today is also using old maps to conduct live firing exercises in the South China Sea and the East China Sea. Because the maps were old, the possibility of Chinese missiles landing outside the live firing areas is extremely high. Ships messing around in the region would conveniently fall target to Chinese fire. Provocative and rogue states sailing their naval ships in the region when China is firing live ammunitions, missiles during exercises are there at their own risk.
If they happened to sail into the path of live ammo or missiles, just bad luck. The missiles have no eyes, and the Chinese forces cannot be blamed as they were using old maps.
All troublemakers be warned. When China conducts live firing exercises in the western Pacific Ocean, you enter at your own risk. You know the danger, you choose to be there. Using old maps is a precedent set by the Americans when they bombed the Chinese Embassy in Belgrade. China will never forget and waiting to use this precedent for live firing practices.
