"I don't remember that about the tribe of Benjamin being wiped off the face of the earth"
Judges 20 and 21 The only remaining 600 men who ran from the battle. The Israeli army slaughtered the entire population of the tribe of Benjamin men, women, children, cattle and burned every city and village in the entire land. Read Judges 19 for the reason for this punishment.
19 was enough. He cut up his concubine into 12 pieces. But those who abused her wanted men instead. Evidently it was for this. Why would he get away with murdering his concubine? True, though, most of the Benjaminites were slain.
This caught my eye:
"Among all this people there were seven hundred chosen men lefthanded; every one could sling stones at an hair breadth, and not miss."
I look for genetic clues in the bible, not appropos to the subject under discussion.