From the perspective of macrohistory, this paper aims at examining the imagination of the world in Roman and Chinese cultures in the pre-imperial period.This study focuses on Tianxia and Orbis terrarum and analyses the manner in which these terms defined the Roman and Chinese conceptions of the globe.Tianxia literally denoted all under heaven.But Chinese chronicles suggest that in practice, it implied a more closed structure.Chinese rulers considered themselves to inhabit the centre of the world and their rule and military campaigns therefore followed the basic structure of the center-sifang-the centre and its four quarters.With the orbis terrarum, the Romans understood their position in the world in linear terms and before Augustus, Rome was never thought to be the center of the oikoumene in both geography and culture.This implies a more aggressive and open world system on the part of the Romans and was reflected in their policy of world conquest.These distinctive differences in conceptions suggest varying attitudes of the Roman and the Chinese societies to warfare which influenced practical policy making in imperial times.