The Radiant Emperor Duology Tome 1
She Who Became the Sun

In a famine-stricken village, a seer shows two children their futures. For the boy, there's greatness. For the girl, nothingness. But China in 1345 lies under harsh Mongol rule - and the other villagers can't imagine how the boy, Zhu Chongba, might find success. And indeed, when bandits seize the village, Zhu Chongba dies. Desperate to survive, the girl steals her brother's identity to enter a monastery.
There, Zhu learns to be ruthless to avoid her fated death. But when her sanctuary is destroyed by war, Zhu is cast back into the world. To stay alive, she must claim her brother's great destin as her own - and rise as high as she can dream.