Christmas in Isaan is non-existent.
Christmas is not celebrated and there is no evidence Christmas even exists.
However, if you happen to go grocery shopping at Lotus’s (British Co.), you will see a few Christmas decorations and hear Christmas music being played.

Aside of some over-priced gift baskets stocked with products most westerners would never think about gifting, there is really nothing else.

No presents to buy, no wrapping paper, no Christmas hats or stockings. Nothing!
It is a solemn reminder that you are now living in Isaan and your favorite holidays are not celebrated in Isaan.
Note: There are some grand Christmas displays in Bangkok and the bigger cities, where there are presumably more westerners with money to spend on Christmas.
Here is rural Isaan it is just another day.

