Before the global tapestry.

Around 10,000 BCE the Neolithic Revolution — the shift from foraging to settled agriculture — set off everything that follows. Surplus food meant population growth, specialization, and (eventually) the first cities. The original civilizations all rose along major river systems: Mesopotamia (Tigris and Euphrates), Egypt (Nile), the Indus Valley (Indus and Ghaggar-Hakra), Shang and early Zhou China (Yellow River), and Olmec and Norte Chico in the Americas. Each developed writing, monumental architecture, organized religion, social hierarchy, and centralized political authority — a package historians call the markers of a complex society.

Between roughly 600 BCE and 600 CE, large land-based empires consolidated regional power and produced political systems we still recognize. The Achaemenid Persians built the first true multi-ethnic empire (satrapies, the Royal Road, religious tolerance). Greek city-states gave us democracy in Athens and the Hellenistic synthesis after Alexander. Rome scaled the republic-then-empire model across the Mediterranean. Han China (206 BCE–220 CE) institutionalized Confucianism, ran a civil service exam, and matched Rome in size. The Mauryan and Gupta empires unified north India and produced classical Hindu culture, Sanskrit literature, and major mathematical advances (zero, decimal place value).

The classical and post-classical periods produced the major world religions and philosophies that shape Units 1–9. Vedic Hinduism in South Asia (Brahman, dharma, caste). Buddhism — Siddhartha Gautama c. 500 BCE — rejecting caste, then spreading along Silk Roads to East and Southeast Asia. Confucianism (Five Relationships, filial piety) and Daoism (wu wei, harmony with the Way) shaping East Asian governance and ethics. Judaism — monotheism, covenant, the Hebrew Bible. Christianity — born from Judaism in Roman Palestine, becoming the Roman Empire’s official religion under Constantine (313 CE). Islam — revealed to Muhammad starting 610 CE, expanding from Arabia into a civilization stretching from Spain to India by 750 CE.

By 1200 the world is already deeply interconnected — Unit 1 drops you into a system that’s been building for centuries. Tang China (618–907) re-opened the Silk Roads and ran Asia’s richest economy; Song China (960–1279) followed with gunpowder, movable type, paper money, and the magnetic compass. The Abbasid Caliphate (750–1258), centered on Baghdad, made Islamic civilization the intellectual center of the world — the House of Wisdom preserved Greek philosophy and produced al-Khwarizmi’s algebra. The Byzantine Empire kept Roman law and Orthodox Christianity alive in the eastern Mediterranean. Western Europe, recovering from Rome’s fall, organized around feudal lords, manors, and the Catholic Church. Mesoamerican Maya city-states had already risen and fallen; the Toltecs and early Mississippian mound-builders were active in the Americas.

The Silk Roads (overland), Indian Ocean trade (monsoon-driven maritime), and trans-Saharan caravan routes are all already carrying goods, ideas, and pathogens by 1200. Three major religious blocs — Christendom (Latin and Orthodox), Dar al-Islam, and the Buddhist/Confucian East Asian sphere — divide Afro-Eurasia. Technologies developed in China (paper, gunpowder, the compass) are starting to diffuse west. Sub-Saharan Africa is connected by trade through Ghana and (emerging) Mali; East Africa’s Swahili coast is plugging into the Indian Ocean. The Americas remain isolated from Afro-Eurasia but have their own complex polities. The world Unit 1 describes is a world being knitted together — Foundations explains how the threads got there.