Two general lithic technological trends are observed in the Upper Paleolithic archaeological record of East Asia. One initially involved the production of large blades, then subsequently emphasized bladelet, and later microblade production. The other entailed an expedient, flake-based technology that does not seem to have changed much over time. The distribution of archaeological sites falling under these two categories is generally divided along an ecological boundary between the Eurasian Steppe to the north and the Summer Monsoon zone to the south. This dissertation details a research program aimed at diachronically comparing blank cutting edge efficiency between Upper Paleolithic assemblages within the Tolbor Valley in northern Mongolia and Shuidonggou 2 in northern China. Results from the Tolbor assemblages indicate an increase in blank cutting edge efficiency over time associated with small flakes, bladelets, and microblades. Results from Shuidonggou 2 indicate that cutting edge efficiency varied little over time, despite changes in raw material use. These findings reveal ecological and technological aspects of the resettling of East Asia by Homo sapiens following their eastward expansion into the region ca. 45,000 years ago.