What did people trade along the Silk Road between East and West?

Picture a road so long it isn't really one road at all — it's a tangled web of dusty trails, mountain passes, and desert tracks stretching thousands of miles between China and Europe. Nobody walked the whole thing. Goods did, though, hopping from trader to trader like a story whispered across a giant playground. We call it the Silk Road, and the name gives away the very first thing that traveled it.
Silk, of course. China had a secret it guarded for centuries: tiny silkworms munch mulberry leaves and spin shimmering thread, which becomes cloth so smooth and light it feels like wearing a breeze. People in faraway Rome adored it. They paid astonishing amounts for it without having the faintest idea where it came from — some Romans thought silk grew on trees.
