Although it's quite extreme, there should be several country blockers App on the Shopify App Store. Otherwise, you can download fraud filter from Shopify and restrict it by IP address.
Males no sense blocking my best selling country for the sake of 6-7 individuals a month that will try paypal to fraud you.
The filter needs to be on the payment method.
Nobody outside China should be able to pay via Alipay either for example.
Standard feature on major shopping cards or with the addition of a small app in carts like OPENCART...