Kanchanaburi was originally established by Rama I as a first line of defence against the Burmese along an old invasion route through the Three Pagodas Pass on the Thailand–Myanmar border.
During WWII the Japanese used Allied prisoners of war to build the infamous ‘Death Railway’ along this same invasion route, from Mae Nam Khwae Noi to the pass. Thousands of prisoners died as a result of brutal treatment by their captors.