Does Shield block IPs by country/geo location?
No, it doesn't.
Geo/country blocking is based on IP addresses and is not entirely accurate. This is the reason on why we don't do IP blocking by geo/country location.
To understand this better, please read the blog article here.
We use our automated IP manager (Automatic IP Black List system) instead.
This system is a part of the IP Manager module. It tracks bad behavior over a set period of time and as soon as it reaches the threshold, the Shield blocks it.
For more information about Automatic IP Black List system, read the article here.