chinese or japanese blue and white ceramic footbath

The piece has no chip or cracks.  There IS crazing of the glaze all over.  When I purchased the piece, it was very dirty and I suspect it was used in the garden as a jardiniere, ergo, the temperature fluctuations causing the glaze to craze.  I did not immerse it in water, I only wiped it down with a damp cloth.  I hope someone can give a definitive answer as to the age of the item from the backstamp.