9th generation from Adam worked bronze and iron.
Genesis 4:22 And Zillah, she also bare Tubalcain, an instructer of every artificer in brass and iron: and the sister of Tubalcain was Naamah.
The earliest iron artifacts date to about 2,000 BC (4,000 years ago). If the world was created 6,000 years ago in six standard earth days then for iron to have been worked in the 9th generation from Adam it would mean that each generation was an average of 220+ years. This begs the question; is some or all of this allegorical or is it all literal?