During two millennia of cultural assimilation and adaptation there had been, to be sure, relatively brief periods of belligerence, such as the Mongol conquest of China and Korea in the 12th century, and two subsequent abortive attempts to conquer Japan by Mongol-led Chinese and Korean troops. There was also an unsuccessful attempt in the 16th century by the great unifier of Japan, Toyotomi Hideyoshi, to conquer China and Korea. But these and other periods of conflict were exceptions to an amicable norm. Indeed, for almost 300 years between 1600 and the late 19th century there was undisturbed peace.