Creating ACL limiting access to U.S. and Europe for VPN access

[marcus.reams]

I know that I can create a control plane ACL to limit the addresses to U.S and Europe, but anyone ever do something like this?  How do you build the list of addresses?

[gbekmezi-DD]

Is there a firewall in front of your VPN concentrators? This link may be helpful:

https://community.cisco.com/t5/firepower/geo-blocking-5508-w-firepower/td-p/3404173

[marcus.reams]

No firewall, but there are routers.  Looks like I may have to do this at the router.