The appellation “city-state” is given to cities which are independent or possess a high degree of autonomy to transact their affairs. Although few of these exist in the modern world—Singapore is a notable example, Geoffrey Parker shows that they constituted important geopolitical units at various times in history, especially in the Middle East, Europe, and parts of Asia. He aims to explain the rise and fall of city-states, and their frequent conflicts with nation-states, empires, and imperial states. At times, city-states thrived under these political/territorial units, but most often they lost their independent status.

Parker organizes the book historically and focuses on the leading city-states at various periods. Their origins can be dated to the Philistines who occupied the eastern Mediterranean around the second millennium BC and founded cities such as Gaza and Ashkelon. Around the first millennium, the Phoenicians set the standard for most subsequent city-states when they became major long-distance traders. The remaining chapters examine the city-states of Greece, Rome, Venice; those of Renaissance Italy and later ones in Russia, the Hanse, Castile; also the city-states of the Netherlands and its predecessors, a return to the city-states of Russia, and the fall and rise of the Hanse cities. The book concludes with a brief examination of globalization and its implications for city-states.

City-states differed according to the degree that they incorporated nearby rural areas as an integral part of their political-economic unit. For the Greeks, the city and immediately surrounding territory were inseparable, and most of their cities were trading centers. In contrast, Rome was a city controlled by a landed elite, and their worldview became the basis for the rise of Rome as a territorial imperial power. Although Parker alludes to the near absence of a powerful merchant trading class, the consequences for Rome's political-economic organization might have been developed more: a powerful rural elite does not necessarily preclude a strong merchant trading class. One might speculate that if such merchants had had a substantial role in the economy of Rome and in the organization of its empire, it might have built an even longer-lasting economic powerhouse to sustain the territorial empire.

Venice's long-term status as a great commercial city-state, without a strong military force over the entire period, was exceptional. Instead, as Parker shows, even if citystates marshaled armies, they ultimately fell to more militaristic city-states or to predator territorial states; the latter generally could marshal greater military power to defeat city-states. Florence fell to that fate, and city-states in Russia fell before the military power of a Moscow-led territorial state. The Hanse city-states, such as Bremen and Lübeck, which focused on merchant trade, persisted for a long period partly because they stayed away from threatening territorial states, but chiefly because they emerged at a time when those states were weak.

According to Parker, location and environmental conditions were important to the development of many city-states. Thus, locations along major roads and rivers (Kiev), at key intersections of trade routes (Cologne), and at advantageous port locations (the Hanse ports) conferred benefits that propelled city-states to positions of influence and riches. The dilemma with such interpretations is that many locations were only one possible set among alternative, equally advantageous locations, and location factors sometimes are read backwards from contemporary beneficial features. Trade routes may predate a city-state's rise, but, often, the merchant traders create the trade routes through their decision making about exchanging capital and commodities. The success of the commercial-financial city-state, for example Florence, probably had much to do with the capacity of a business-political elite to control long-distance economic exchange. Moreover, some of the most successful city-states, such as Venice, which rested amid sandbanks and swamps, or Amsterdam, which was virtually built on water, occupied poor physical environments.

The significance of long-distance merchant traders and their descendents, such as financiers, as the basis of city-states pervades the book. Yet Parker does not fully follow up that theme to make it central to his argument. Many of his explanations for the trajectories of city-states are political in tone. Superior territorial powers arise to take over the city-states. This military power cannot be dismissed; however, the merchant traders and financiers typically were the very basis of the rise and decline of citystates. Still, Parker's major contribution is to demonstrate across time and place the significance of the geopolitical conditions within which city-states emerged, functioned, and declined. Most of them possessed limited military power relative to territorial states, especially after about the first millennium AD. City-states continually needed to negotiate their role with the powerful territorial states, and, if the cities were recognized as threats, their survival was in jeopardy. This book serves as a broad overview of city-states in history.