Where does “brī” come from?
brī (Old Saxon) comes from Proto-West Germanic brīw, from Proto-Germanic brīwaz, from Proto-Germanic bʰréy-u-s ~ bʰr̥y-éw-s, from Proto-Indo-European bʰr-ey-, from Proto-Indo-European bʰer- — to bear, carry.
Ancestry of “brī”, step by step