The Wall of Storms By Ken Liu

Kuni Garu, now known as Emperor Ragin, runs the archipelago kingdom of Dara, but struggles to maintain progress while serving the demands of the people and his vision. Then an unexpected invading force from the Lyucu empire in the far distant west comes to the shores of Dara—and chaos results.

But Emperor Kuni cannot go and lead his kingdom against the threat himself with his recently healed empire fraying at the seams, so he sends the only people he trusts to be Dara’s savvy and cunning hopes against the invincible invaders: his children, now grown and ready to make their mark on history.