> can't understand why they didn't think of starting geographical exploration and colonization
They did. Just as a land power. Modern China includes conquered territory of the Mongolians, Turkics and Tibeto-Burmans, among others [1].
(The proximate answer is the Ming-Qing transition [2] overlapped with the Age of Discocery [3].)
> except for China and the US, no one cares who the product comes from
This is breathtakingly wrong, as a simple perusal of every single country's trade restrictions would show. (Even if you're talking about the population versus policy, show me a market where no premium is paid for luxury products imported from such and such distant land.)
