Curry is basically a mix of every over the top spice in the Idian, Thai, or Islander Kitchen. Depending on what country, and what region, and what county/district or city, or part of city that you are from, curry means a completely differen't taste look and combination of these spices. There is no easy substitute, but that being said, you could take ginger powder, allspice and premixed chili powder and mix to taste, and basically you would have curry powder, South Indian style. The Thai versions tend to be either dramatically sweeter, or hotter, or both.
I hope this helps you!
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