Very few traders traversed the entire Silk Road. Instead, they'd move back and forth between towns, selling to traders who'd take the goods further toward their destination, with everybody marking up prices along the way. So what'd they trade? Well, silk, for starters. For millennia, silk was only produced in China. It is spun from the cocoons of mulberry tree-eating worms, and the process of silk making, as well as the techniques for raising the worms, were closely guarded secrets since the lion's share of China's wealth came from silk production. The Chinese used silk as fishing line, to buy off nomadic raiders to keep things peaceful, and to write before they invented paper.