On the basis of a wide selection of primary sources including a number of late-nineteenth-century Russian documents from varied archive collections in Uzbekistan, the author reconstructs the destiny of Central Asian Jews converted to Islam, many of whom continued to secretly perform Judaic rites. The article focuses on the change entailed by the Russian conquest of Central Asia and by the creation of the Turkistan Territory. On the one hand, the author reminds the influence of Russian conquest for the return to Judaism of those Chalahs residing in the territories annexed by Russia after 1868 and for dozens of Chalah families who managed to escape from Bukhara to Russian Turkistan. On the other hand he also casts a crude light on the limitation measures taken by Russian administration in several southern districts of the Territory, as soon as the 1870s-80s, against the settling of more Chalahs from Bukhara. He also describes the eviction of the Chalahs from the cities of Turkistan from 1910 onwards ― a period characterised by the continuation of conversion of Jews to Islam (notably of migrants from Iran), and by the rejection of all Chalah requests for Russian citizenship. It is to these recent developments that the author attributes the non-return to Judaism of many Chalahs after the conquest of the Emirate of Bukhara by the Red Army in 1920.