Admittedly I haven’t done a lot of international travel with a bike, but my suggestion is to keep your expectations reasonable. If the whole reason you’re visiting another country is to ride a trail or trails that are supposed to be amazing, you may end up disappointed. However, if your primary reason for traveling is to experience another culture, meet interesting people, and see new sights, then it doesn’t matter so much if your bike breaks, the weather doesn’t cooperate, or the trails aren’t in great shape.
Most of us (in the USA anyway) have excellent mountain bike trails to choose from, which sets the quality bar pretty high. Use the mountain bike as a vehicle to explore a new part of the planet–not just as a toy for entertainment–and you’ll have a great experience.
I would agree with Jeff. If you set out to find trails yourself and unfamiliar with the area then asking on the day can result in disappointment. Booking a guide can also be a disappointment too. Do some research. Does the area already have a MTB setup if not can be hard work.
I just went to Switzerland and Germany thinking I was going to ride amazing singletrack trails and came away very disappointed. Loved the countries and had a great time there but their trail system cannot compare to what you find here in the good ole USA if you ask me. I would suggest you leave the bike at home and rent if you find areas that you feel are worth riding. Dragging a bike around on trains, planes or autos would be a hassle.