I dunno Teri... they invaded Tibet in 1950, and Vietnam in 1979. Both wars were short; the first they won, the second they lost. They of course claim the Tibet awar s merely a police operation reclaiming usurped Chinese territory.

I suppose it's more correct to say that since their self- contained empire was penetrated in the 18th century, they've mostly been too weak to launch wars, and prior to that they were the whole world and it wasn't worth looking outside.