This paper presents partial results of a large-scale fieldwork project of interdisciplinary studies on Middle Paleolithic settlement in the western Tian Shan piedmont. Within the project, a complex of newly discovered open-air, loess sites named Katta Sai was excavated. The Katta Sai complex of archaeological sites is comprised of two main sites of Middle Palaeolithic: Katta Sai 1, and Katta Sai 2, both recognized by excavations, and a number of surface findings in the vicinity. The surrounding landscapes are mid- to high-mountains- the most western part of Chatkal Ridge, representing the north-western piedmont of Tian Shan mountains.
The excavations allowed to identify a new variant of human adaptation in the regional Middle Paleolithic. What is particularly interesting in Katta Sai assemblage, the use of rounded river pebbles restricted the manufacturing process heavily. In majority the river pebbles of effusive rocks brought from the nearby river gorges were used for knapping. The technological analyses shown that we deal here with predetermined flake technology in Levallois type, focused on obtaining thin triangular flakes or even blades. However, the manufacturing scheme was adjusted to the poor quality of raw material. The use of very hard, poorly silicified rock, did not allow to derive the sequences of small, precise removals. In a consequence the predetermination of blanks' shape had to be designed more by a careful intensive preparation of a striking surface.