There's been a global economy ever since the intense Phoenician commerce in the Mediterranean and since the silk road, and rather than preventing, it has fueled dozens of wars.
For example, the famous steel of Damascus was made with Indian ingots containing a little tungsten that were transported to Africa and then to Damascus. It doesn't get much more global than that. A Muslim Indian nobleman could make out a check to a horse trader in Andalusia and receive his horses maybe one or two years later, long before Italian bankers claimed to have invented checks.
Japan attacked the US because it desperately needed oil to keep fighting in China, not because it felt like it.
China will attack as soon as a really big drought threatens with major famine or when the depressed economies of its trade partners cannot support its economy or when a natural disaster weakens the US or when oil reserves dwindle.
The Middle East has a few hundred million people without any industry and so incompetent at fighting that they prefer to blow themselves up. As soon as oil reserves approach depletion (as Chinese, Indonesian and Indian demand explodes) or the US develops fission, its only source of income will disappear and chaos will develop. The only cement that binds it is Islam, but they have managed to weaken the bond with bitterly opposed branches (Shiite, Sunny, etc,).