The widespread distribution of microblade assemblages has been discussed in connection with human migration and cultural transmission across Northeast Asia during MIS 2. However, there has been no clear consensus among researchers on the interrelationships between the emergence of microblade assemblages and the construction of human population dynamics in Northeast Asia. Recent evidence makes systematic verification still necessary to determine whether the scenario of simple migration from North Asia is sufficient to explain spatiotemporal variation in lithic assemblages in different regions of Northeast Asia. Elucidating the diversity of reduction processes and knapping techniques among lithic assemblages across Northeast Asia is important for understanding of human population dynamics. This chapter reviews the current state of the study of microblade technology in Northeast Asia, focusing on the issues of the definition of microblades and microblade technology and their impacts on the current interpretations.