Complex sentence: Mîm was one of the last of the Petty-dwarves who lived together with his two sons, Ibûn and Khîm, at Amon Rûdh in west Beleriand, where he kept a secret treasury.
Split into simpler sentences: Mîm was one of the last of the Petty-dwarves. He lived together with his two sons, Ibûn and Khîm, at Amon Rûdh in west Beleriand, where he kept a secret treasury.