What would the world be like if Alexander the Great died at age 86 instead of at age 33 and did not contract swamp fever in Babylon? In this ATL, he unified most the known world including Rome, Gaul, Hispania, and Carthage. He solidified the political structures and undertook transportation constructions to cement the Hellenistic Empire that spanned from Atlantic Ocean to the Pacific Ocean. In addition, the fusion of Greek and Persian cultures was more successful than that in OTL. His success resulted in almost two millenniums of an imperial dynastic system (similar to that in China) in a unified Europe, North Africa and Southwest Asia.
The unified political and cultural system strengthened the Empire to resist threats and rebellions. Economy was also more active because trading was protected within the Hellenistic empire. However, the unipolar structure also diminished regional diversity and damped cultural development in most places, although some such as Rome or Carthage flourished. Many cities also grew substantially in size during a span of 400 years under Hellenistic rule.