I suppose the broader question may be, why do we have the Roman Empire and the Eastern Roman Empire represented separately, but the Qin and Yuan dynasties are represented together as "China"? Some may suggest the Roman Empire under Trajan and the Eastern Roman Empire under Basil II are completely different cultures, but could the same not be said of the Qin and Yuan dynasties, which reigned 1,400 years apart? Additionally, Basil II and Trajan are (comparatively) only 900 years apart and represent the same polity in the same line of succession. The only thing Kublai and Qin Shi Huang seem to have alike is that they ruled over the same area. By that logic, should Suleiman rule over the Eastern Roman Empire as well? Or are Kublai and Qin combined into China because of the transfer of the Mandate of Heaven? Should Peter be available as leader of the Eastern Roman Empire then, as Moscow claimed itself to be the Third Rome? Or Philip II, since the last Byzantine emperor granted his imperial rights to the Spanish throne? Ultimately, the separation of the Roman Empire based on time period, but not China, seems arbitrary and inconsistent to me. Addendum: would you rather see China split or Rome and Byzantium combined?