Christian Topography (547) by the Alexandrian monk Cosmas Indicopleustes , who had travelled as far as Sri Lanka and the source of the Blue Nile , is now widely considered the most valuable geographical document of the early medieval age, although it received relatively little attention from contemporaries. In it, the author repeatedly expounds the doctrine that the universe consists of only two places, the Earth below the firmament and heaven above it. Carefully drawing on arguments from scripture, he describes the Earth as a rectangle, 400 day's journey long by 200 wide, surrounded by four oceans and enclosed by four massive walls which support the firmament. The spherical Earth theory is contemptuously dismissed as "pagan".   
Tianxia ( 天下 ; pinyin : Tiānxià ) literally means " under heaven "; and Tianchao ( 天朝 ) means "Heavenly Dynasty". These terms were usually used in the context of civil wars or periods of division, in which whoever ends up reunifying China is said to have ruled Tianxia , or everything under heaven. This fits with the traditional Chinese theory of rulership in which the emperor was nominally the political leader of the entire world and not merely the leader of a nation-state within the world. Historically the term was connected to the later Zhou Dynasty (c. 1046–256 BCE), especially the Spring and Autumn period (eighth to fourth century BCE) and the Warring States period (from there to 221 BCE, when China was reunified by the Qin state ).
Maoism also required a belief that Chinese civilization had developed in accordance with “objective” Marxist historical laws, from a primitive band to a socialist society. Mao-era archaeologists thus strove to use their findings to prove these laws, legitimizing the status quo . As Xia Nai, the director of the Institute of Archaeology himself, wrote in a 1972 paper, “We archaeologists must follow the guide of Marxism, Leninism, and the thought of Mao Zedong, conscientiously fulfilling the great guiding principle of Chairman Mao, to ‘make the past serve the present.’” It’s no surprise then that during the Cultural Revolution meetings were convened under such absurd headings as “Using the Antiquities Stored in the Temple of Confucius in Qufu County to criticize Lin Biao and Confucius.” Meanwhile, revolutionary sloganeering found its way into scientific publications alongside the data.