Why would a flourishing civilization, advanced for its time, suddenly cease to exist, its inhabitants gone and its architecture abandoned? Conspiracy theorists offer all manner of offbeat explanations including alien abduction, but in the case of these 12 societies, the causes were likely more mundane: natural disasters, climate change, invasions and economic irrelevance. Still, we don’t know – and likely never will – exactly what happened to bring about the end of the Khmer Empire of Cambodia, the Minoan society of Crete or two ancient civilizations right here in the United States.
Home to one of the greatest man-made architectural wonders of the ancient world, the Indus Valley Civilization (known at the height of its influence as the Harappan Civilization) was among the largest early urban settlements on any continent. Located in modern-day Pakistan, the Indus Valley Civilization thrived 4,500 years ago and was then forgotten but for local legends until ruins were excavated in the 1920s. Sophisticated and technologically advanced, this civilization, including the famous Mohenjo Daro, featured the world’s first urban sanitation systems as well as evidence of surprising proficiency in mathematics, engineering and even proto-dentistry. By the year 1500 BCE, the Indus Valley Civilization was virtually abandoned, possibly after invasion by Indo-European tribes or a collapse in agriculture due to climate change.
Once one of the most powerful empires of Southeast Asia, the Khmer civilization spread from modern-day Cambodia out into Laos, Thailand, Vietnam, Myanmar and Malaysia and is best known today for Angkor, its capital city. The empire dates back to 802 CE. Other than stone inscriptions, no written records survive, so our knowledge of the civilization is pieced together from archaeological investigations, reliefs in temple walls and the reports of outsiders including the Chinese. The Khmers practiced both Hinduism and Buddhism and built intricate temples, towers and other structures including Angkor Wat, dedicated to the god Vishnu. Attacks from outsiders, deaths from the plague, water management issues affecting the rice crops and conflicts over power among the royal families likely led to the end of this empire, which finally fell to the Thai people in 1431 CE.
‘Anasazi’ is the modern name for the ancient Pueblo Peoples who inhabited the ‘Four Corners’ area of the southwestern United States at the junction of the states of Utah, Arizona, New Mexico and Colorado. Their civilization emerged around the 12th century BCE, and remains best known for stone and adobe structures built along cliff walls including Cliff Palace in Mesa Verde National Park, the White House Ruins and Pueblo Bonito at the northern rim of Chaco Canyon. This architecture evolved into amazing multi-story dwellings that were often only accessible by rope or ladder.
The ancient Puebloans did not necessarily “vanish”; they did, however, abandon their homeland for reasons unknown in the 12th and 13th centuries CE. Many experts as well as modern Puebloans, who claim the ancient Puebloans as their ancestors, believe that deforestation and droughts caused internal conflict and warfare, causing these ancient people to disseminate.
In what is now Veracruz and Tabasco in the tropical lowlands of south-central Mexico was once a grand Pre-Columbian civilization that constructed incredible ‘colossal heads’, practiced bloodletting and human sacrifice, invented the concept of the number zero and essentially laid the foundation for every Mesoamerican culture that was to follow. The Olmec civilization might even have been the first civilization in the Western hemisphere to develop a writing system, and possibly invented the compass and the Mesoamerican calendar. Dating to around 1500 BCE, the Olmec civilization wasn’t ‘discovered’ by historians until the mid-19th century. Its decline is blamed on environmental changes caused by volcanic eruptions, earthquakes or possibly damaging agricultural practices.
A major participant in trade with the Roman Empire and Ancient India, the Aksumite Empire – also known as the Kingdom of Aksum or Axum – ruled over northeastern Africa including Ethiopia starting in the 4th century BCE. Theorized to be the home of the Queen of Sheba, the Aksumite Empire was likely an indigenous African development that grew to encompass most of present-day Eritrea, northern Ethiopia, Yemen, southern Saudi Arabia and northern Sudan. The empire had its own alphabet and erected enormous obelisks including the Obelisk of Axum, which still stands. It was the first major empire to convert to Christianity. Axum’s decline has been variously blamed on economic isolation due to the expansion of the Islamic Empire, invasions, or climate change which altered the flood pattern of the Nile.
Named after the mythical king Minos, the Minoan civilization of Crete wasn’t rediscovered until early in the 20th century, but since then we have uncovered fascinating puzzle pieces of an ancient civilization that began flourishing over 7,000 years ago, hitting its zenith around 1600 BCE. Centers of commerce appeared around 2700 BCE, and as the civilization advanced, palaces of greater and greater complexity were built and rebuilt following series of disasters – likely earthquakes and eruptions of the Thera volcano. One of these palaces was Knossos, the ‘labyrinth’ associated with the legend of Minos, which is now a major archaeological site and tourist attraction. But sometime around 1450 BCE, there was an unknown disaster that the Minoans apparently weren’t able to recover from, and the civilization met its downfall. In moved the Mycenaeans – who would later join the Minoans in the void of vanished empires. Fun fact: the Minoan script, known as Linear A, remains undeciphered.
The largest settlements in Neolithic Europe were built by the Cucuteni-Trypillians of modern-day Ukraine, Romania and Moldova. This mysterious civilization, which flourished between 5500 BCE and 2750 BCE, is characterized by its uniquely patterned pottery and by its bizarre habit of burning its own villages to the ground every 60 to 80 years. The villages were rebuilt again and again, on top of the ashes of the old ones. About 3,000 Cucuteni-Trypillian archaeological sites have been identified including what may be the world’s oldest saltworks. Like so many other civilizations, the Cucuteni-Trypillians may have been wiped out by climate change, but other theories suggest that they gradually blended with other groups until their own culture was lost.
The ancient Nabatean civilization occupied southern Jordan, Canaan and northern Arabia starting in the sixth century BCE, when the Aramaic-speaking Nabatean nomads began gradually migrating from Arabia. Their legacy is epitomized by the breathtaking city of Petra, carved into the solid sandstone rock of Jordan’s mountains, and they are remembered for their skill in water engineering, managing a complex system of dams, canals and reservoirs which helped them expand and thrive in an arid desert region. Little is known of their culture and no written literature survives. They were overtaken by the Romans in 65 BCE, who took full control by 106 CE, renaming the kingdom Arabia Petrea. Sometime around the 4th century CE, the Nabateans left Petra for unknown reasons. It’s believed that, after centuries of foreign rule, the Nabatean civilization was reduced to disparate groups of Greek-writing peasants who were eventually converted to Christianity before their lands were seized altogether by Arab invaders.
Few Americans realize that we have the remains of a lost ancient civilization right here in the United States – in Illinois, just across the Mississippi River from St. Louis, Missouri. The Cahokia Mounds Historic Site is all that is left of an indigenous civilization of the Mississippian culture, settled around 600 CE. The inhabitants of Cahokia did not seem to keep written records, but preserved at this World Heritage Site are a series of grass-covered man-made ‘mounds’ as well as pottery and other artifacts. Cahokia was once the largest urban center north of the great Mesoamerican cities of Mexico and may have once been home to as many as 40,000 people – greater, in the year 1250 CE, than the population of London, England, or that of any American city that was to come until Philadelphia around the year 1800. Cahokia was abandoned around 100 years before Europeans arrived in North America, possibly due to environmental factors or invasion of outside peoples.
Unlike the Minoans before them, the Mycenae didn’t flourish by trade alone – they set out to conquer, and expanded into an empire that overtook much of Greece. Hitting its peak right around the time the Minoans disappeared, the Mycenaean civilization enjoyed five centuries of domination before vanishing sometime around 1100 BCE. Hellenic legend holds that the Mycenae defeated the possibly mythological Troy, and the empire’s artifacts have been found as far away as Ireland. In fact, this culturally and economically wealthy civilization has left behind a wealth of art, architecture and artifacts. What happened to the Mycenae? Natural disasters are possible, but most experts believe that it was either foreign invaders or internal conflict that brought about the end to this once-great empire.
More of a collection of peoples that shared a similar culture than an empire, the Moche civilization developed an agriculturally-based society complete with palaces, pyramids and complex irrigation canals on the north coast of Peru between about 100 and 800 CE. While they had no predominant written language, leaving us few clues as to their history, they were an extraordinarily artistic and expressive people who left behind incredibly detailed pottery and monumental architecture. In 2006, a Moche chamber was discovered that was apparently used for human sacrifice, containing the remains of human offerings. There are many theories as to why the Moche disappeared, but the most prevalent explanation is the effect of El Nino, a pattern of extreme weather characterized by alternating periods of flooding and extreme droughts. Perhaps this explains the Moche’s bloody efforts to appease the gods.
Very little is known about the Clovis culture, a prehistoric Paleo-Indian people that were thought to have been the first human inhabitants of North America. Archaeologists have tentatively dated artifacts found at an archaeological site near Clovis, New Mexico at 11,500 RCYBP (radiocarbon years before present), equal to about 13,500 calendar years, but dating beyond 10,000 years is considered unreliable. The artifacts, bone and stone blades known as Clovis points, are among the only clues we have that this group – technically not a civilization – ever existed. In the last thirty years, remains of possibly older human activity have been discovered, calling the Clovis’ status into question, but whether or not they were first, they did disappear rather abruptly. Some speculate that the Clovis overhunted, compromising their own food supply, or that climate change, disease and predators took their toll. Others believe that the Clovis didn’t disappear at all, but simply dispersed into the beginnings of early Native American tribes.