While modern civilizations extend to every continent except Antarctica, most scholars place the earliest cradles of civilizations—in other words, where civilizations first emerged—in modern-day Iraq, Egypt, India, China, Peru and Mexico, beginning between approximately 4000 and 3000 B.C.
These ancient complex societies, starting with Mesopotamia, formed cultural and technological advances, several of which are still present today. “A great many of the details of modern life, not just in the Middle East and the West, but across the world, have origins that go back for thousands of years to the ancient cultures in their respective regions,” says Amanda Podany, author and professor emeritus of history at California State Polytechnic University.
Here’s a look at six of the earliest civilizations—and the legacies they left to the world.
1. Mesopotamia, 4000-3500 B.C.
Meaning “between two rivers” in Greek, Mesopotamia (located in modern-day Iraq, Kuwait and Syria) is considered the birthplace of civilization. The culture that grew up between the Tigris and Euphrates rivers is noted for important advancements in literacy, astronomy, agriculture, law, astronomy, mathematics, architecture and more, despite near-constant warfare. Mesopotamia was also home to the world’s first urban cities, including Babylon, Ashur and Akkad.
“Mesopotamia is the earliest urban literate civilization on the globe—and the Sumerians, who established the civilization, established the ground rules,” says Kenneth Harl, author, consultant and professor emeritus of history at Tulane University. “Those who know how to research and write run the civilization and everyone [else] does the grunt work.”
The cuneiform writing system, used to establish the Code of Hammurabi, is among the most famous Mesopotamian advancements. They also created the base 60 numeric system, which led to the 60-second minute, 60-minute hour and 360-degree circle. And it was Babylonian astronomy that first divided the year into 12 periods named after constellations—what the Greeks would later evolve into the zodiac.
Persia eventually conquered Mesopotamia in 539 B.C. Centuries of upheaval followed.
“Within the three millennia in which ancient Mesopotamia flourished, innumerable individual kingdoms came and went, and a few empires rose and fell for various reasons,” says Podany, author of the forthcoming book Weavers, Scribes, and Kings: A New History of the Ancient Near East. “But at its core, the civilization was recognizably the same from around 3500 BCE to as late as 323 BCE—and, many would argue, beyond that. The region was rarely unified, but the civilization was very stable.”
2. Ancient Egypt, 3100 B.C.
Perhaps the most romanticized of past civilizations, ancient Egypt stood as one of history’s most powerful empires for more than 3,000 years. Set along the fertile Nile River and at one time extending from today’s Syria to Sudan, the civilization is most known for its pyramids, tombs and mausoleums and the practice of mummification to prepare corpses for the afterlife.
Harl, author of the forthcoming book, Empires of the Steppes: How the Steppe Nomads Forged the Modern World, says Egypt's use of labor to undertake architectural projects—such as the pyramids—was unrivaled. “The ability to amass 100,000 men to assemble the great pyramid in 2600 B.C. is just not matched anywhere," he says.
The Egyptians also proved extremely skilled at agriculture and medicine, he adds. And they developed exquisite sculpture and painting traditions, as well.
The ancient Egyptians also left a legacy of monumental writing and mathematics systems. The cubit, a measure of length roughly the span of a forearm, was key to designing the pyramids and other structures. They developed the 24-hour day and 356-day calendar during this time. And they established the hieroglyphic pictorial writing system, followed by the hieroglyphic system that used ink on papyrus paper. The civilization came to an end in 332 B.C. when it was conquered by Alexander the Great.
READ MORE: 14 Everyday Objects of Ancient Egypt
3. Ancient India, 3300 B.C.
In ancient India, where Hinduism was founded, religion held great importance, Harl says, along with great literary traditions and incredible architecture. The Upanishads, or sacred Hindu texts, include the ideas of reincarnation and the caste system based on birthright, both of which have endured into modern times.
Unlike other ancient civilizations, the Indus River Valley Civilization, built in the Indus River Valley (modern-day India, Afghanistan and Pakistan) does not appear to have been war-torn. Historians and archaeologists instead point to sophisticated, organized city planning, complete with uniform baked-brick homes, a grid structure and drainage, sewage and water supply systems.
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The collapse of the Indus Valley, around 1700 B.C., is often credited to migration prompted by climate change or possible tectonic movement that caused the Saraswati River to dry out. Others cite a great flood.
4. Ancient China, 2000 B.C.
Protected by the Himalayan Mountains, Pacific Ocean and Gobi Desert, and situated between the Yellow and Yangtze rivers, the earliest Chinese civilizations flourished in isolation from invaders and other foreigners for centuries. To stop Mongols from the north, they built barriers seen by some as early precursors to the Great Wall of China, built later in 220 B.C.
Generally divided into four dynasties—Xia, Shang, Zhou and Qin—ancient China was ruled by a succession of emperors. The civilization is credited with developing the decimal system, abacus and sundial, as well as the printing press, which allowed for the publication and distribution of Sun Tzu’s The Art of War, still relevant more than 2,500 years later.
Like the Egyptians, the ancient Chinese were able to mobilize populations to build massive infrastructure projects. The construction of the 5th century-era Grand Canal, which links the Yellow and Yangtze rivers, for example, allowed vast numbers of military forces and goods to move across the country.
“China is perhaps the most successful centralized state in human history," Harl says. "And at several points in human history is without a doubt the greatest civilization that stayed on the globe.”
READ MORE: China: A Timeline
5. Ancient Peru, 1200 B.C.
Peru served as the cradle of civilization to a number of cultures, including the Chavín, Paracas, Nazca, Huari, Moche and Inca. Archaeologists have unearthed evidence of metallurgy, ceramics and advanced medical and agricultural practices from within these groups.
The Incas did not develop a writing system; instead they used pictures and symbols. But they did use a knot-based accounting system, built paved roads on rugged terrain connecting towns and settlements and created sophisticated agricultural and architectural innovations.
Smallpox and other diseases, introduced to South America by the Spaniards, ravaged the Inca populations, Harl says, causing an internal weakening that helped the Francisco Pizarro-led conquest of 1532. “So many people were being carried off by disease—they had no immunity,” he says. “So rather than the state itself weakening in any significant way, it was disease introduced by the outside that helped prepare for the Inca toppling of civilization in Peru.”
6. Ancient Mesoamerica, 1200 B.C.
Parts of today’s Mexico and Central America were once home to a number of Indigenous cultures, beginning with the Olmec around 1200 B.C., followed by the Zapotec, Maya, Toltec and, ultimately, the Aztecs.
Fertile farmland led to agricultural advances, with corn, beans, vanilla, avocado, peppers, squashes and cotton becoming important crops. Pyramid-style temples, intricate pottery, stone monuments, turquoise jewelry and other fine arts have been uncovered. Scholars believe the Zapotec developed Mesoamerica’s first written calendar and writing system, while the Mayans are noted for their advancements in mathematics, hieroglyphics, architecture and astronomy.
The nomadic Aztecs founded Tenochtitlan (today’s Mexico City) in 1325 on small islands in Lake Texcoco, and the city became a booming market for trade. The Aztecs used a 365-solar calendar along with a 260-day ritual calendar, practiced human sacrifice and bloodletting, used a form of picture writing and created works of art with terracotta, feathers, mosaics and stone.
The Hernán Cortéz-led 1519 Spanish invasion, aided by Mesoamerican foes of the Aztecs, brought the Aztec civilization to an end by 1521. “When Cortez showed up, the Aztecs were having great difficulty maintaining control over their subject tribes,” Harl says. "They were greatly hated, and Cortez gave enough advantage to all those disadvantaged subjects to topple the Aztec Empire."