Venkatesh Rao@vgrTrade? That's what coins are forQuote TweetThe New York Times@nytimes·Oct 5, 2016It's an archaeological mystery: How did Roman coins end up in the ruins of a 12th-century castle in Okinawa, Japan? http://nyti.ms/2drndJH5:13 AM · Oct 5, 20161 Retweet10 Likes