Left: Sword of Goujian, King of Yue of China’s Spring and Autumn period (771 to 403 BCE), unearthed in 1965 with untarnished condition. Experts believe that the chemical composition, along with the almost air-tight scabbard, explains the exceptional state of preservation.

Right: Spear of Fuchai, King of Wu (archrival of Guojian), unearthed in 1983.