Along with ancient technologies such as the wheelbarrow, Westerners also picked up the newest advances. The magnetic compass, first mentioned in a Chinese text in 1119, had reached Arabs and Europeans by 1180, and guns moved even faster. During the thirteenth-century Mongol invasion of China, Eastern craftsmen learned how to make gunpowder oxidize quickly enough that it would explode, not just burn, and started using this nasty new trick to propel arrows from bamboo tubes. The oldest known true gun—a foot-long bronze tube found in Manchuria that could fire lead bullets—probably dates to 1288.
