Zomia

The story starts in 13th=century Daxingfu, the capital of the Jin Dynasty, a kingdom exhausted by the Mongol invasion. Nergui, a former slave boy and a prodigy who can learn any language, lost everything in the "first air raid in history" launched by the Mongol army. Remembering the words of his best friend Bator, "If you want freedom, you must fight," Nergui vowed revenge against the Mongols. His weapon of choice is "words," and his opponent is the most powerful empire in history. A former slave boy will combine "knowledge" and "blood" in this epic historical drama!

(Source: Kodansha, translated)