Genghis Chron, in laymen's terms simply means the dankest chronic ever. It is a play off of the great conquerer Genghis Khan who pretty much ruled Asia. See marijuana
"dude last night, I smoked the fattest blunt filled with Genghis Chron"
"no way man, you couldn't have smoke Genghis Chron, we don't even have that shit in our state"