Ryuugen no Houjutsushi

A life spared. Entrusted with hopes. Carrying it all, the solitary sorcerer races across the land! The guardians of the "Dragon Veins," the energy essential to life—that is the role of a sorcerer. Li Xiaoming, the most powerful of them all, and his disciple Yu Chun, spent their days hunting down those who plotted to seize the Dragon Veins. But then, one day, an unexpectedly formidable enemy appeared!?

(Source: Kadocomi, translated)