Amaterasu was part of a Goa'uld delegation, including Lord Yu and Camulus that sought an alliance with the Tau'ri against Ba'al who has seized control of Anubis' base and Kull Warriors following Anubis' defeat and had gained a great deal of power.
Clearly seeking the weapon used to defeat Anubis for themselves, the Goa'uld tried to bluff and threaten their way into securing Dr. Elizabeth Weir and Stargate Command's cooperation. However, thanks to Dr. Daniel Jackson's counsel, there was not much Amaterasu or her companions could do to persuade the Tau'ri to ally themselves with the Goa'uld. Amaterasu briefly considered letting information slip to Ba'al that the weapon the Tau'ri used to destroy Anubis was out of commission, which would have led Ba'al to conquer Earth.
While Camulus asked for and was granted asylum with the Tau'ri, Amaterasu and Lord Yu left empty-handed, but not before she denounced Camulus as a traitor and a coward. (SG1: "New Order, Part 1", "New Order, Part 2")
Within a year, Amaterasu and Yu were the only ones capable of mounting any effective resistance against Ba'al, though the Tok'ra believed that their efforts were doomed to fail. Amaterasu was not among the System Lords to whom Ba'al sent a peace offering, and her fate following the collapse of the Goa'uld Empire is unknown. (SG1: "It's Good to Be King", "Reckoning, Part 1")
- In an alternate reality, Amaterasu had once ruled PX7-455 and was worshiped as a god by its inhabitants. The natives believed that she had abandoned them and therefore represented an easy target for the Ori, who sent a Prior to the planet. The SG-1 of that reality claimed to have investigated the situation on 9X7-455 immediately before their arrival in our reality. (SG1: "Ripple Effect")