Thebes, known to ancient Egyptians as Waset, was a city on the eastern bank of the Nile and the capital of Egypt during the Middle and New Kingdom periods. It resided across the river from the Valley of the Kings and was home to a cult of Amun which operated out of Karnak.
Sometime around 38 BCE, the city was plagued by a "curse"; various deceased pharaohs from the New Kingdom were seemingly brought back from the dead and were terrorizing and killing civilians in the region. The news of these events eventually reached the Hidden One Bayek of Siwa and his ex-wife Amunet, who sent the former to meet her contact in the city.
In 38 BCE, upon arriving in the harbors of the city, Bayek was greeted by Sutekh, an Egyptian who welcomed him to the city. They were soon interrupted by the manifestation of an apparition of Nefertiti, who attacked the residents and soldiers. Having defeated the apparition, Bayek met with Amunet's contact outside Luxor, an Egyptian smuggler named Merti, who owed Amunet a favor some time prior. Bayek handed a parcel to the smuggler, who discussed the details surrounding the curse: a relic was stolen from a pharaoh's tomb in the Valley of the Kings, which supposedly brought down the curse onto Thebes. Merti informed Bayek to head to the black market, believing the merchants there to have more information on the curse. She also told Bayek to look for the God's Wife of Amun Isidora in Karnak, should he have more questions.