he article presents unpublished documents which shed new light on the history of the archaeological exploration of Eastern Turkestan: letters of M.M. Berezovsky and A. Grünwedel sent to each other and to S.F. Oldenburg and W.W. Radloff respectively, as well as official papers. The main subject of the documents in question is the division of the spheres of archaeological excavations in Eastern Turkestan between the Prussian Imperial Turfan Expedition and that of M.M. Berezovsky in 1906.