The Lords of Andúnië named for their ancestral home of Andúnië were descended from Silmariën, daughter and oldest child of Tar-Elendil the fourth King of Númenor. The laws of Númenor at that time would not allow her to rule as queen, so she wedded Elatan of Andúnië and took up residence there. Their son Valandil would be named the first Lord of Andúnië in about the seventh century of the Second Age.
Throughout the Second Age, the Lords of Andúnië became leaders of the Elendili, or Elf-friends, for remaining friends with the Elves and faithful to the Valar. This was despite opposition and eventually persecution from the King's Men.
At the end of the Second Age, Númenor's estrangement from the Elves and the Valar under the evil guidance of Sauron corrupted Númenórean society. Seeking pardon of the Valar for the wickedness of the Númenóreans, Amandil the Faithful, Lord of Andúnië, sailed into the west but was never heard of again.
His son Elendil, the last Lord of Andúnië, did not join Ar-Pharazôn's grand armada to attack Valinor, and instead fled with his sons Isildur and Anárion and many of the Faithful to Middle-earth, where they founded the lines of the Kings of Gondor and Arnor.
Elendil brought with him the Sceptre of Andúnië, the instrument of his lordship, which became a hereditary emblem of royal authority in Arnor, along with the Ring of Barahir. It later became known as the Sceptre of Annúminas and by the Third Age thought to be the oldest artifact made by Men in Middle-earth.