World population, about 545 million
Pangaea reunited. In the century after 1492, West Europeans mastered the winds and currents of the world’s oceans. The shock to the rest of the world would be comparable in some ways to the earlier shock resulting from the spread of nomadism on the Eurasian steppes. In the Americas, the immediate results were devastating, with the loss of most of the population to introduced diseases, helped along by conquest and enslavement. But the spread of new crops and animals in both directions also helped fuel a population boom in the Old World.
Mega-empires. In Eastern Europe and Asia, the results of West European expansion by 1600 were less dramatic. There the landscape was dominated by huge empires: Russia, the Ottomans, Safavid Persia, Mughal India, Ming China. These have sometimes been called “gunpowder empires,” emphasizing the role of cannon in establishing centralized power. But they could also be considered the aftermath of the Mongol conquests, either arising from the overthrow of Mongol rule (Russia, China) or claiming direct Mongol descent (Mughal India). In other words, these empires developed in centrifugal fashion, with power collapsing at the old Mongol center, and new states arising along the Mongol marches.
Charlemagne + 800. Another centrifugal episode of state formation took place in Western and Central Europe, on a smaller scale, over a longer period of time. As the Carolingian Empire disintegrated, new states arose along its marches, in Iberia, in France, England and Scandinavia, and in eastern Germany and neighboring, mostly Slavic territory. Meanwhile the core of the former empire, including western Germany and northern Italy, remained fragmented. By earlier Roman or Asian standards, medieval states in Europe, even when they controlled large areas, were feeble things. The state’s power to collect taxes had more or less collapsed, and Medieval monarchs were forced to concede substantial privileges to their subjects in exchange for their support. By 1600, however, military competition had produced more powerful absolutist states. Medieval liberties survived best in lands where military threats had been less intense, on islands (England and Scotland), on an isolated peninsula (Scandinavia), in the mountains (Switzerland) or soggy lowlands (Holland), or just far from the madding crowd (Poland).