I don't know. The Wall is supposed to be impassable except through the tunnels the Night's Watch carved in the ice. Mayhaps she found an old, forgotten tunnel. And it's the Long Night not nights.

It's supposed to be a time when a terrible winter came. It lasted a generation. The Sun never rose. Entire families froze in their homes. Food ran out. People would kill each other for what was left. Some even ate each other. That's when the White Walkers came. Old Nan called them the Others. They're cold dead things that hate life. They wield swords of ice so cold they shattered steel. And they could raise the dead to fight for them. Anything, it didn't matter. People, animals, so long as they were dead.