Traditional, structural theories of international relations may have eschewed the importance of geography and territory to understanding international conflict, but the past 50 years of quantitative scholarship have returned geography and territory to the fore of the discipline. The importance of geography and territory to the study of international conflict first emerged in the discipline of political geography and the early foundations of peace science. Subsequent empirical analyses demonstrated a robust connection between geography, particularly disputed territory, and all phases of inter-state conflict. Explanations for this robust relationship emerged concurrent to the empirical findings. The theoretical arguments are eclectic and focus on territoriality as human instinct, the tangible and intangible value of territory, and whether conflict over territory conforms well to implications from the bargaining framework. Though traditionally the domain of inter-state conflict scholars, civil conflict scholarship has greatly informed this research program on geography, territory, and conflict by expanding and enriching its theoretical arguments and empirical implications. The future of territorial conflict scholarship should focus on reconciling different theoretical arguments about the emergence of peace after World War II, wrestling with the future of territorial conflict as more territorial disputes are settled, providing richer data on territorial claims, and exploring the implications of global climate change for future conflict over scarce and changing waterways and maritime/river boundaries.