At the time of her birth, the Haladin had settled in Thargelion, in East Beleriand. After her father and her twin brother Haldar were slain in an Orc raid, Haleth became leader of the House. She held her people together for seven days until Caranthir and his men drove out the orcs and ended their siege on the Haladin. Seeing, at last, what great courage dwelt in the hearts of some men, Caranthir did Haleth great honour by offering her people land in the north under the protection of the Eldar. However, out of pride and a desire to remain independent, she declined the generous offer and instead gathered what remained of her people after the orc siege and led them to Estolad.
Against the desire of her people, Haleth led the Haladin even further west to the land between the Mountains of Terror and the Girdle of Melian. Suffering much hardship and loss, many regretted taking part in the journey. Eventually, Haleth led her people to the relative safety of the Forest of Brethil on the western border of Doriath where they settled for the duration of the First Age. The Haladin then became known as the House of Haleth. She remained chieftainess of the Haladin all her days and retained a picked bodyguard of women.
When Haleth died, her people raised a green mound for her in the heights of the forest - Tur Haretha, the Ladybarrow, or Haudh-en Arwen in Sindarin. Having never married, the leadership of the Haladin passed on to her nephew Haldan, son of her brother Haldar, when she died.