The first millennium BC saw in and around the Mediterranean an unprecedented growth in demography, economy, technology and politics, resulting in the first true superpower. A milder climate and the discovery of iron enabled a revolution in productivity, literally feeding urbanization and the establishment of stronger states. The dispersed Greeks lived in city states near (natural) sea ports and championed maritime trade and colonization, like Phoenicians. Only Athens managed to become the early metropolis, until Alexander the Great's Macedonian dynasty united Greece and conquered the Persian empire, only to fall apart after his early death into several empires, wealthy Egypt being the main, new capital Alexandria as new leading metropolis. Yet Rome, one of many tiny states in central Italy, thanks to superior collaboration and organization, started unifying them and annexing territories around, like grain producer Sicily and Iberian silver mines after its triumph over rival Carthage. A volcanic cloud in Alaska possibly sealed the fate of Egypt when Cleopatra, last 'Greek pharaoh' by Caesar's hand, allied with candidate-ruler Marc Anthony and followed him in suicide after Octavian's total victory. Rome grew by raising armies of citizens, but has just switched to mercenaries, who enabled their generals to overrule the political elite, yielding civil war. Climate worsening to the north and east caused massive migrations, which even the best organized empire ultimately couldn't resist, despite turning to allied tribes to ward off the new threats.