Limit FTP connections by area

Is there any (simple) way to deny FTP connections based on the general physical location? I plan to use FTP as a simple cloud storage for me and my friends. I use an odroid c2 (similar to raspberry pi but uses arm64 architecture) running Debian 8 with proftpd and ufw as my firewall. Ftp server runs on a non-standard port which I prefer not to mention here. I want to do this to increase the security of my server.