She may have changed her name to Gaia Caecilia (called Gaia Cyrilla in Boccaccio's On Famous Women) when she arrived at Rome, although some Roman historians also commonly spelled her name Caia Caecilia or Caia Cyrilla.
The daughter of a powerful Etruscan family in Tarquinii, Etruria, Tanaquil thought her husband would make a good leader, but since he was the son of an immigrant, he wouldn’t stand a chance in getting a top political position in Tarquinii, where they lived. Knowing this, Tanaquil encouraged him to immigrate to Rome. She had a talent for spinning and weaving, but is most known for her strong prophetic abilities, which helped her install Tarquin as king and later Servius Tullius as the next king. While on the road to Rome, an eagle flew off with Tarquin's hat and then returned it to his head. Tanaquil interpreted this as a sign that the gods wanted him to become a king. Pliny says that a statue was dedicated to her as Gaia Caecilia in the temple of Semo Sancus.
Tanaquil's prophecy was eventually realized for Tarquin - he eventually became friends with King Ancus Marcius, who made Tarquin guardian of his children. When the king died before his children were old enough to become successors to the throne, Tarquin used his popularity in the Comitia to be elected the fifth king of Rome. He ruled from 616 to 579 BCE.
Tanaquil also played a role in the rise of Servius Tullius, the sixth king of Rome. Raising him as her own child, Tanaquil believed Servius would be the next successor to the throne. Her dreams would be realized when, one day Servius was sleeping and his head was surrounded with flames. The fires danced around his head without hurting him and when Servius awoke, the fire disappeared. Taking this as an omen, Tanaquil knew Servius would one day be king. When Tarquin was murdered, Tanaquil hid his death from her subjects, instead telling them that Tarquin appointed Servius as a temporary king until he got better. After gaining the people’s respect and commanding the kingship, Servius and Tanaquil announced Tarquin’s death. Tanaquil had a daughter, who married Servius Tullius, and two sons, Lucius Tarquinius and Arruns Tarquinius, who would marry daughters of Servius.
Tanaquil was a skillful artisan in the art of working with wool. Queen Gaia was so much admired by the Romans of her day that it was a public decree that any new bride entering their royal palace would announce their name as "Gaia" when asked. This was said to be an omen of future frugality for these women and showed the simple living style of the time period.
Although the same person, Gaia Caecilia and Tanaquil really had two different distinct personalities. She was supposed to have exercised special influence over new Roman brides and there are interesting amusing stories related to her and certain customs of ancient Roman marriages.