Because why not?
I am willing to ship a single package with an object back 1,000 years -- no more, no less -- to a place of your choosing. I will try to match a recipient to the best of your wishes, i.e. "To the smartest chemist in China". The rules are:
-- Package is a maximum size of two cubic feet (1'x2' box or whatever variant)
-- No writing or pictographs may be sent. I will allow incidental writing such as the engravings on a pistol but no attempts to communicate ideas, instructions or warnings. An oil painting of a tree or photo of your butt would probably be allowed; a picture of Conquistadors slaughtering native Aztecs would not. I'll be the sole judge of what qualifies.
-- No live organisms or pathogens of any sort, living or dead.
-- The object may have separate parts that can reasonably be considered a "set" such as a set of silverware, a socket wrench kit or a gun with a clip of ammunition. Sticking ten random things in the box is not allowed.
-- If you wish a recipient, he will be aware that the box appeared "by magic" and probably pay special attention to it.
Will you try and change the course of history or just send a photo of your butt?