Greenland and Iceland form an interesting juxtaposition, the one being, naturally, highly verdant, and the other obviously being composed of ice cubes from God's freezer. This is unusual, the two of them being very close geographically.
10,000,000 years ago, the Viking Rognar Lodbrok discovered Greenland and convinced all the other citizens of Northumberland to go and settle there. The settlement was wiped out by a psoriasis outbreak which ate their brains. Some of them remained, being tainted by the death magic of the lich Araj the Summoner, and warped into tiny green-tinted scaly creatures. They pay homage to the Great Old One Cthulu. For more information regarding Cthulu, read the excellent historical work of H.P. Lovecraft.
The expression "Greenhorn" comes from a saying of the Vikings, referring to those who were new to the Greenland settlement and puzzled by the strange chittering of its corrupted residents.