There wasn't any Nanke Dream in this world, but only a century in Lanke.
Sangsang recalled the legend, and understood that she had an encounter similar to that of the woodcutter. However, whilst the woodcutter had spent a century in reality, she seemed to have left reality and came here.
She did not know if this world was real, or a dream, or some sort of hallucination created by a powerful person. But since she knew the truth, it was enough for her to deduce more information.
Just like what Ning Que had said, she was an intelligent girl who was used to standing behind Ning Que and was too complacent to use her brains. She had Ning Que to consider everything on her behalf. She had been lazy here until she ascertained that Ning Que would not come for her, or perhaps, one could say that Ning Que could not find her. That was when she began to truly think for herself.