I've been to Thailand several times but never Chiang Mai - usually Bangkok and south.
My f-i-law was based out there in WW2 running 'the Hump' as in flying to China to bring troops down to Thailand to the Allies. Early on they had a salutary lesson in loading the plane with 115 Chinese soldiers and when they arrived, there were 90 something....and then it dawned on them what had been happening. They had never flown before, needed to go to the loo, and stepped out of the door....
Japanese underneath, 'aaaazoha - newa Alli bombsa coming down.'