I think you were trying for an em dash. Remember, you need them at both the beginning and end of the parenthetical phrase. Also, if you're using a regular keyboard I think you need two hyphens for each em dash. The Silla Kingdom's trade--in both products and ideas-- shaped modern Eastern Asia with the spread of traditional medicine, silk, wool, ginseng, calendars and clocks. Silla evolved as a major hub for maritime trade in East Asia and eventually became a maritime power.

You need to remove the hyphen because you don't want the phrasal verb. trade-in = exchange trade in = enterprise in

thank you for the help :)