From "The Cambridge History of Inner Asia" (Cambridge, 1990), p.275
According to al-Bakri (d. 1094), the Pechenegs up to the year 400/1009-10, were followers of "the religion of the Magi." This statement may indicate some Zoroastrian or Manichaean influences. It may also refer to a shamanistic cult. After that period, according to our sources, Islam began to make some headway amongst them (f.n.)
Footnote: A. Kunik, V. Rozen, Izvestija al-Bekri i drugikh avtorov o Rusi i slavjanakh, pts. 1-2 (pt. 1, Supplement to the Zapiski Imperatorskot Akademii Nauk, xxxii, 1878), p. 43.
Islamic perspective (reference), from "The Encyclopedia of Islam", (Cambridge, 1954), p.1018:
Officially, they (referring to another Hungarian group) called themselves Christians and they disguised their Islam, in contrast to the Maghariba/Pechenegs*, who overtly professed the Muslim faith ...
*Maghariba (Arabic: المغاربة al-Maghāribah, meaning "Westerners").
They are often referred to as "Maghariba" in Islamic texts of the time, which makes it difficult for Latin (Western) scholars to know whom exactly these "Westerners" were. The problem has persisted to present-day research.