Which of our ancestors made the most sturdy, and effective battle ready swords

Which of our ancestors made the most sturdy, effective and battle ready swords? By sturdy, I mean wont break, and effective I mean can still deliver the power necessary to get through countermeasures and do damage.

Was it the Persians, Romans, Greeks, Franks, Vikings, Japanese, Chinese, Arabs, etc? Did I leave anyone out? I dont know how to post a poll. Feel free though.

I imagine in battle, your sword is going to smack into a lot of shields, armor, and other metal blades...

Which of our ancestors made the most sturdy, and effective battle ready swords