Keeping control of the restive North has been a constant nation-building challenge for the southern Thai monarchs, which is a good part of the reason why this train line is here in the first place. Particularly a hundred years ago, a train line offered a way to project force into an area with unprecedented speed.
This place is a fine example of this: in the reign of Rama V – the man who first had this railway built – a group of jewel miners from the hills to the West rebelled against the crown, stormed the town of Phrae – about 20km up the valley to the North – and killed the local ruler. The king ordered one of his leading Generals to go rout out the bandits from the hills and make an example of them.
For this mission, the general set up his camp here: Den Chai. When his mission was completed, enough people stayed on to turned it into this town. The town’s strategic purpose was resurrected during the 1st World War, when a field army base was located in Den Chai, and even today the 12th Cavalry maintain the a base here, named after the General who quelled the initial rebellion: Phraya Chaiyabun.
Its perhaps for these strategic reasons that the line you’re travelling on takes such a circuitous route – it essentially heads North-South from here to Bangkok, and rougly East-West from here to Chiang Mai. There seems to have been more direct ways to lay the track, and perhaps, and which would have traversed less mountain ranges. But cutting across more of the north allowed more control of it.
Today there is also talk of extending the line from the town of Den Chai north along this valley and up to Chiang Rai.