Just finished Dan Carlins: Wrath of Khans podcast series. He mentioned a Kublai that led a scouting force that took out Georgia and then returned back to Mongolia. Was that Kublai Genghis's grandson, the future khan, or just a friend/associate?
Actually Dan is talking about the Mongol General Subutai: http://en.wikipedia.org/wiki/Subutai
Source: Also listen to Wrath of the Khans :)