This poem is from Bai Juyi's Song of Eternal Sorrow. The first four sentences of the original text are: The emperor of China longed for the beauty that might shake an empire. After many years in office, he searched and never found it. Until a child of the Yang family grew up in the inner room, almost before she grew up, and no one knew her.
"Raised in the inner room, no one knows her" means that the ancient woman had little contact with the outside world before she was married, so it was difficult for outsiders to see her face clearly and understand her personality.