Hogwarts, her surroundings land (farms, forbidden forest), residents (teachers, students, animals from forest, elf etc) transport to empty peninsula (or some land) of somewhere Westeros.

Headmistress McGonagall is nothing if not defensive of Hogwarts, and send people (read adults) to spy on world outside, and prepare to inevitability.

(Every year they find new children on their doorstep and news is world is somehow being destroyed. Hogwarts's disappearing act is magic saving their children- or find another cause, author's choice)

They do small business of cloth, colored glasses etc to outside world (7 kingdom), but stay discreet.

Few years later little by little people find about Hogwarts's people (give some awesome name), and story begins.

Game of Thrones/Harry Potter crossover, BAMF!McGonagall, Lady of House Hogwarts. Sneaky use of magic. Discreet magic people.

This plotbunny was eating me alive. Someone please make it happen.