The Children (Chinese) created the Others (virus) to fight the first men (Americans). The Others (virus) got out of control and finally crossed The Wall (The Great Wall) to invade the lands of the first men (USA)...
From the books: In the Tyrion chapter where he's "traveling" with Catelyn to the Vale, the three men-at-arms in service to Lord Bracken who are escorting them are Lharys (Italy), Mohor (Iran), and Kurleket (Spain). Larry, Mo, and Curly.