@CarlManvers2019 At the very least it was rather frowned upon, and had - since 13th century, when it was still (relatively) widespread - largely disappeared. This might offer a more detailed view.
By act of RoB, Kingdom of Hungary of 1470 is dropped into Essos, between Forrest of Qohor and Painted Mountains, just before the start of the A Game of Thrones. How do events proceed from there, and what does Matthias do?