There is one difficulty of course: The Eastern Civilizations had hardly any contact with the more Western ones. That is: the Indo-Eurasian factions (Scythians, Indians, etc.) were politically disjoint from the Eastern cultures (due to Himalayas, Pamirs, Tien Shan, but mostly the Himalayas). Culturally, the story was otherwise... So how is this for another idea: "0 A.D.: Silk Road" - This will be everything Indo-Eurasian: Persians, Near-East, Scythians, Indians, Sarmatians, everyone. "0 A.D.: Far East" - The Far East. Not only developmental warfare, but even intra-cultural warfare (Han against Han, political wars, etc.)