During my research into the history of Krabi Krabong in Thailand there is very little information, especially regarding the development in Northern Thailand.
One thing I have uncovered is very interesting in that during the 19th Century Temples were places that taught a great many things and swordsmanship was one of the things taught. This was due to the fact that many ex soldiers took to the robes to gain merit for the harm they had done on the battlefield and still passed their skills on to the next generation to help them protect their families and villages and also to prepare them for war.
First the practitioner would be taught meditation, Samadhi to help concentration and discipline the mind for the training to come, the Wat was a perfect place with no outward distractions.
Unfortunately I believe many of these schools died out when the Abbot or monks who were teaching passed away, but it partly explains how the art survived and evolved.
It is interesting to note that the events are similar to the Shaolin temple in that warrior monks trained in fighting arts and Buddhism, but the main difference in Thailand is the monks were just, that they had renounced the warriors path and taught to help preserve and protect.