I read a fantasy book where the city of the religios "elders" was destroyed because they misused some secret powers. Destruction rained down from the skies. The main protagonist was a boy whose father died in the destruction. He was somehow called to greatness. (he saw visions or ghosts or such). There were wildlings that lived in a forest who had old magic and were led by a young girl. There was a powerful Lord who had wealth and influence in the south and vied for power with other powerful families. There was a land bridge to unknown lands that could have been where the original people came from.
When I started reading Game of Thrones the land and influential