Hello, You mention a Tang horse, but show only the feet, then there is a jar and some details which it is not so clear if they belong together. Is the opening besides the jar something of the horse? The order of the pictures is a bit confusing.
First, I can't help with Tang wares, I know too little about these. Maybe a visitor knowing more about thesecan help?
Assuming that the other detail pictures are all of the same white glazed jar, it is necessary to see the bottom of ANY Chinese porcelain or pottery item before an evaluation of age can be done. The bottom is the most important place.
As far as I can see the jar could be a thousand years old, but it could also be only a hundred years old. It is antique, apparently, but how old is difficult to tell with monochrome items. A (very) close picture of the glaze showing the crazing would also be of interest.
Please be aware that reliable identification of items like these is difficult via pictures only. It may be easier with Ming and Qing dynasty items. So any comments may only be considered an opinion and not an appraisal.