muckpuk,
There is absolutely no reason why you can not have Tulips in Thailand. However, with that said, there are a couple of issues I think you should be aware of:
1) Bulbs arriving in December will not have a long enough chilling period to bloom at the normal time unless you can find "pre-chilled" bulbs.
2) From my understanding of Thailands climate, you will have difficulty getting spring-flowering bulbs to bloom outside using conventional methods. It just does not get cold enough for a long enough period of time.

With all of that said, I would recommend that you use a practice of "forcing" spring-flowering bulbs and treat them as an annual. This will allow you to enjoy bulbs but not in the conventional way. There is some really good articles on this website at the link below and they have a pretty good newsletter you might be interested in to.

Here is a link that might be useful: Gardening Resource