Köçümkulkïzï, Elmira and Daniel C. Waugh. "Religion." In Traditional Cultures in Central Asia." Silk Road Seattle (2001), http://depts.washington.edu/silkroad/culture/religion/religion.html.

Köçümkulkïzï and Waugh argue that "there is a syncretism between pre-Islamic religious tradition and Islamic norms, a fact which explains some of the distinctive features of Central Asian Islamic practice."  Further they state: "It is difficult for most Central Asians today to distinguish today between that which is Islamic and that which is shamanic or non-Islamic."  To fill out this argument they discuss shamanism, the Yasawi and Naqshbandi Sufi orders, formal/orthodox Islam of historic Bukhara and Samarqand, and sacred sites (mostly in Kyrgyzstan).  Among the sacred sites they mention and provide photos of petroglyphs, balbals, burial sites, trees (some with strips of cloth and others with bones), and cairns/oboos.  Other than mosques located nearby some of these sites and the presence of Arabic writing, it is unclear the relationship of these sites to Islam.  The last example of sycretism cited is the Gur-i Amir Mausoleum in Samarqand, Uzbekistan about which the author's state, "a pole with a horse tail has been erected over one of the graves in the interior, a feature characteristic of oboo ritual sites in other regions of Central Asia which were not influenced by Islam. "  Other interesting quotes are as follows:

Walsh, Harry H. “Turkic-Speaking Peoples.” In Muslim Peoples: A World Ethnographic Survey, edited by Richard V. Weekes, 422-427. Westport, CT: Greenwood Press, 1978.

This chapter is mostly linguistic and shows the diversity of Turkic people in Central Asia.  Here is one of the few quotes about Islam from page 427: "The Kirgiz, alone among the eastern Turks [Kirgiz-Kipchak and Khakas-Yakut], practice Islam, albeit with a shamanistic substratum."  Descriptors: 1970s, bibliographic, chapter, identity, linguistics, Soviet, W; syncretism