Maturing civilizations experience a period of turmoil and adjustment at this Progress Level. Developments continue in architecture, commerce, metallurgy, and mathematics. Wider dissemination of information becomes possible thanks to more advanced printing techniques. Sea communications dominate in the later part of this stage of development, and sturdy seafaring carracks and galleons open the door to the next Progress Level.
As populations increase and knowledge of agriculture evolves, an increasing percentage of the population relocates into growing cities and towns. Toward the end of this Progress Level, the feudal system, in which a small class of nobles ruled a large population of agricultural workers, begins to collapse. Specialized crafts develop, universities appear, and the middle class is born. The first corporations emerge in the form of trade guilds. The evolution of strong systems of trade and finance tends to distribute a society's wealth more evenly among its members, diluting the power of the nobility.
Tools of warfare undergo a significant revolution. Sophisticated chain and plate armors protect warriors from harm, and elaborate fortifications become something of an art form. Toward the end of the Middle Ages, the introduction of simple gunpowder weapons signals the imminent end of knights, heavy armor, and organized armies of swordsmen.