You're talking about the Magna Mater, who was brought in 205/204 with the assistance of the Pergamenes. Magna Mater is an aspect of Cybele, although she wasn't especially important until Augustus, who featured her in iconography relating to the Troad, due to the gens Julia's status as one of the Trojan Families--even then, though, Magna Mater's actual worship was extremely isolated, restricted pretty much entirely to the Palatine, although other cult centers spread pretty rapidly through the west. Cybele had a number of cult centers in Anatolia, and the Magna Mater is thought to have originated from either the center at Ida or the one at Pessinus, although Varro thought that the Magna Mater originated as a form of Cybele directly at Pergamum