Here it comes

The Conrad-Demarest Model of Empire: Basic Principles for the Roman, Han Chinese, and Gupta Empires

Necessary preconditions for the rise of empires:
State-level government:
Rome: republic then empire with emperor
Han: kept most of Qin centralized government in place
Gupta: decentralized; regionalism
High agricultural potential in the area:
Rome: wheat, grapes, cattle
Han: wheat, millet, pigs
Gupta: cotton, wool, calico (chief revenue – tax on agriculture)
An environmental mosaic
Rome: Alps, Mediterranean Sea, forests, Tiber and other rivers, hills
Han: Tianshan mountains, Yellow and Yangtze Rivers, loess soil, Pacific Ocean.
Gupta: Indus and Ganges Rivers, Thar Desert, Deccan Plateau, Himalayas
Several small states with no clearly dominant state (power vacuum)
Rome and other city-states on Italian peninsula; surrounding states in Mediterranean (Greek states, Egypt, Judea, Syria, Cyprus, Gaul, Romania, Spain, Sicily, Sardinia, Carthage, etc.)
Han: Qin broke into smaller states
Gupta: regional leadership/rule.
Mutual antagonisms among those states:
Rome: rivalry between pastoralists in hills and agriculturalists in plains
Han: Warring States period before Qin unification
Gupta: Hinduism vs. Buddhism; women losing rights.
Adequate military resources:
Rome: soldiers first recruited only from peasant class on Italian peninsula; population inexhaustible.
Han: Soldiers recruited from peasant class within the entire empire; population inexhaustible.
Gupta: ability to make metal weapons; social system extremely strict, therefore military was particular in choosing (relatively peaceful time). Powerful army maintained tight control.
The primary reason a state succeeded in empire building was:
An ideology supporting personal identification with the state, empire, conquest and militarism:
Rome: “republic” based on citizenship of free men; citizenship ensured loyalty to the state and brought taxes into the state treasury;