From the mid-second century b.c. to the late first century a.d., the armies of China’s Han Dynasty (206 b.c.–a.d. 220) defended their territory against the marauding forces of the Xiongnu Empire, a ...

A 15th-century manuscript shows trees bearing (clockwise from top left): sweet apples, jujubes, lemons, cherries, dates, and sour apples. By 7,000 years ago, people in New Guinea were cultivating ...