Was Black Sabbath or Led Zeppelin the first ever METAL band in history?

Zeppelin helped lay the foundation, but weren't quite metal. They had like 1-3 songs that were "metallic", and that isn't enough songs to qualify as a metal band considering how many songs they had period. Black Sabbath were the first metal band, though Scorpions formed earlier (though weren't yet playing metal). Don't forget Deep Purple either. I heard "Black Night" and thought it was some NWOBHM band, but the song was written in the 60's, not to mention, "Highway Star" was practically proto-thrash back in like '71.