sounds like Wise Men but guess they're Wise People as some will be girls. Just needs to be exotic and rich-looking.
try
-embroidered kimono or silky dressing gown, big sash, chopsticks in hair?
-buy / borrow a shalwar kameez? (would suggest a sari but they're almost impossible to put on if you're under 11)
-long 'ethnic' top of yours as a dress with a shiny belt and lots of costume jewellery?
NB check if she needs a gift to carry - the more weirdly shaped the better as everyone else's will be square. Try a Finish Powerboost thing suitably covered.