As AliMarie said--silks and spices...and there was more. Europeans were always on a quest for gold and they weren't about to leave Asia an unturned stone. That's why the British were wild about India in particular.
From Cathay came not just silks and spices, but also fire arms, gun powder, ceramics technology (which is why it's called china) and they became enamored of what Europeans call "Delft Blue" but which actually originated in Cathay (China's old name) and which couldn't have come into being even in China without trade with the Arabs, which gave them the blue part (cobalt).
There's also the matter of Asia coming to Europe in the form of Ghengis Khan, Golden Horde, and the Uyghurs, which ultimately founded the Ottoman Empire...all from China. Although of Turkic ethnicity, the Uyghurs are why Turkey's silk industry rivals that of China itself.