Where does “sang-froid” come from?

sang-froid (French) comes from French sang, from Old French sanc, from Vulgar Latin sanguem, from Latin sanguinem, from Latin sanguen, from Latin san-, from Proto-Indo-European h₁sh₂-én-, from Proto-Indo-European h₁ésh₂r̥ — blood.

sang-froid (French): sang-froid, calmness, calm