I eat a lot of curry here in Taiwan.
Recently, I stumbled upon an Indian restaurant here with a map of the curry trade, spreading out from India through today's Malaysia and into Japan and other places through the Indian ocean.
It made me think, how did a food which I presume started in India, reach east Asia?
I do not have an answer for you, but I will add a little depth to your question and hopefully get my own little curiosity answered.
Japan has 2 traditions for curry both of which are called curry, one is a brown thick curry and the other varies wildly but is generally Nepalese or Indian (if the signs outside all the restaurants are to be believed). I wonder if this has anything to do with the answer you are looking for, but I hope we both learn something interesting when a real food historian comes along.