Hi Igor, >letters is Ta(great) and one is maybe from Qing >dynasty.Can this be true? It could be anything. But, please be aware that while it is possible, it is not likely. I don't think a reign mark would appear on a traditional storage jar widely used by the general population. It is more likely that this is the name of the manufacturer, impressed before firing. To voice this more carefully, as mentioned before, such jars are still in use; but not only are they still in use, they are also still being produced. As such, please be open to that it might be vintage only. This said, I can't see a character in the enlargment, only what seems to be an impressed horizontal line at the top. It is somewhat difficult to see lines clearly with that background. You could try to make the mark more visible. For example, you could try rubbing chalk into the lines of the characters, then wiping the jar surface clean so that only the lines remain. The chalk can be easily removed later with a brush. However, impressed marks or stamps are sometimes carelessly applied, so that they are not fully visible. I will try to read it, but can not promise anything.