The key is to be comfortable with the frontier market (FM) that you are investing in. Many FM indexes are heavily weighted in the Gulf States - Gulf Cooperative Council (GCC). So, pick a GCC only ETF, like MES, and then pick the country specific ETF's that look like winners. In any event, over the long term, if you pick your countries and you don't overweight GCC - FM will increase risk adjusted returns to any diversified portfolio.