In China, a railway has been discovered in south west Henan province near Nanyang city. It was carbon dated to be about 2200 years ago from Qin dynasty. The rails are made from hard wood and treated against corrosion while the sleepers or railway ties made from wood that were not treated and therefore have rotted. Qin railway sleeper was designed to allow horses to gallop through which would go to the next rail station which would then be swapped for a fresh horse. The railway is theorized to have been used for transportation of goods to the front line troops and to fix the Great Wall.