Timothy Snyder, the Richard C. Levin Professor of History at Yale, continues his course on the origins of Ukraine by examining the Grand Duchy of Lithuania, a medieval state far larger and more consequential than its modern borders suggest. He traces how Lithuania absorbed much of the former Kyivan Rus territory and became a multiethnic, multilingual polity governing Slavic lands alongside its Baltic core. Snyder situates this history within his larger argument about how the Kyiv state's legacy was inherited and contested by later powers, and how that inheritance shapes Polish, Russian, Jewish, and Ukrainian self-understanding. The lecture is part of a full Yale course tracing Ukraine's history from medieval statehood through the twentieth century, and treats the Grand Duchy as a crucial, often overlooked, foundation for understanding the region's later political development.