The Brilliant Young Scholar

He transmigrates to ancient times and finds his family dirt-poor! No problem. With knowledge from the twenty-first century, he can invent a few things and improve their lives! Before he knows it, he’s become a local tycoon. Life couldn’t be sweeter! Barbarians invade? Then he’ll form a cavalry, build cannons, and beat the hell out of them! If you disrupt my peaceful life, no enemy is too far away to punish!