The famous Upper Paleolithic sites at Kostenki are located on the west bank of the Don River outside the city of Voronezh (Russian Federation). An international project at Kostenki (and nearby Borshchevo) during 2001-2004 and 2007-2008 focused on excavation and analysis of the early Upper Paleolithic occupations (i.e., those antedating 30,000 years ago). The earliest occupations underlie a volcanic tephra (CI Y5) that is 40,000 years old and provides an important chrono-stratigraphic marker at Kostenki and Borshchevo. Most of the sites are found along large side-valley ravines on what was, at the time, the first terrace above the river. Springs are active today in the ravines around Kostenki, and analysis of the sediments indicates that they were active during early Upper Paleolithic times, and may have been a draw for both large animals and people. During these times, the occupants of the Kostenki sites hunted groups of horses (sometimes other large mammals, including reindeer) in the ravines and butchered the carcasses at or near their camps.