1. Indus Valley Civilization

Once inhabiting an area about the size of western Europe in what is now Pakistan and western India, the Indus Valley or Harappan Civilization thrived from 3300 to 1300 BC, although the area was settled all the way back to 7000 BC. 

Despite being one of the largest ancient civilizations, not much is known about the Harappan civilization, mostly because their language has never been deciphered. We do know that they built over one hundred towns and villages including the cities of Harappa and Mohenjo-Daro, each of which was built with an organized layout, and a complex plumbing system with indoor toilets. Evidence suggests that the Harappan had a unified government and that there were no social classes. There is also no evidence of military activity so it is likely that they lived in peace. They were skilled astronomers and were well versed in agriculture, growing wheat, barley, peas, melons, sesame and cotton (becoming the first civilization to produce cotton cloth) and domesticating several animals including cattle and elephants. 

There are several theories as to what happened to the Indus Valley civilization. Some people believe that they declined because of changes to their environment, such as a decrease in the size of the Ghaggar Hakra river system or the cooler, drier temperatures that are also evident throughout the Middle East. Another popular theory was that the Aryans invaded them around 1500 BC. 

2. Anasazi Civilization

The Anasazi or Ancestral Puebloans were a Native American culture that emerged in the Four Corners area of the United States (where New Mexico, Arizona, Colordo, and Utah meet) around 1200 BC. 

The early Puebloans were hunters and gatherers who lived in shallow pit houses. Later they developed horticulture and began farming maize, beans and squash. Also found at Anasazi archeological sites are greyware pottery, elaborate baskets, reed sandals, rabbit fur robes, grinding stones and bows and arrows. In the Pueblo II and Pueblo III eras the Anasazi carved whole towns out of nearby cliffs like those at Mesa Verde and Bandelier or they constructed them out of stone or adobe mud like Chaco Canyon. These towns hosted many cultural and civic events and were connected to each other by hundreds of miles of roadways. 

Around 1300 AD the Ancestral Puebloans abandoned their cliff houses and scattered. Many scholars believe that, after a population explosion, poor farming methods and a regional drought made it difficult to produce enough food. Due to this lack of food, the Anasazi moved either along the Rio Grande or on the Hopi mesas, and therefore many modern Pueblo Indians believe that they are the descendants of the Anasazi. Recent studies prove that this climate change could not explain the decline of the Anasazi alone and suggest that social and political factors like a violent conflict led to their end, instead. 

3. Minoans

Named after the legendary King Minos, the Minoans inhabited what is now Crete from 3000 to 1000 BC. 

In Greek mythology, Minoa was the land of Cretan Bull and it’s son, the Minotaur- a mythical half-man-half-bull that lived in the labyrinth and killed anyone who entered. In reality, the Minoans were the first known civilization in Europe.  Today all that is left of the Minoan civilization are their palaces and the artifacts found within. The Minoan civilization was one of social organization, art and commerce. Early Minoans spoke a language that we call Linear A, which during later periods was replaced by Linear B, both of which were based on pictographs. There is no evidence of any military culture found in the Minoan palaces and it seems their power was purely economical. Even though the Minoans fell, their culture was inherited first by the Myceaneans and from there by the Hellenistic Greeks.  

Many scholars believe that the Minoans were wiped out by a volcanic eruption on the island of Thera (now Santorini), but there is evidence that they survived. However, the eruption would have killed all plant life thus leading to starvation, and damaged their ships leading to economic decline. It is also believed that during this time they were invaded, possibly by the Myceaneans. 

4. Clovis

A prehistoric Native American people, the Clovis culture dates back to 10,000 BC. Centered in southern and central plains of North America they are archeologically recognized by chipped flint points called Clovis points. 

They used these points on the end of spears to hunt big game like mammoth and bison and small game like deer and rabbits. The Clovis people were the first human inhabitants of the New World and are considered the ancestors of all North and South American indigenous cultures. Many scholars believe that they crossed the Beringia land bridge from Siberia to Alaska during the ice age and then headed south to warmer climates. 

There are several theories around the disappearance of the Clovis culture. The first states that a decrease in megafauna along with less mobility in their culture led them to branch off and form new cultural groups, like the Folsom culture. Another theory is that the mammoth and other species became extinct due to over hunting, leaving the Clovis without a viable food source. The final theory revolves around a comet that crashed to the earth around the Great Lakes region and significantly affected the Clovis culture. 

5.  Cucuneti-Trypillian Civiization

In Romania they are the Cucuteni, in the Ukraine they are the Trypillians and in Russia they are the Tripolie: a late Neolithic culture that flourished between 5500 BC and 2750 BC. 

The Cucuteni-Typillian culture was matriarchal, the women were the heads of the household and also did the agricultural work and made pottery, textiles and clothing. The men were hunters, tool makers and were responsible for looking after domestic animals. Their religion was centered around the Great Mother Goddess who was a symbol of motherhood and agricultural fertility. They also worshipped the bull (strength, fertility and the sky) and a snake (eternity and eternal movement).

One of the main theories about the end of the Cucuteni-Trypillian culture is the Kurgan hypothesis, which states that they were conquered by the warlike Kurgan culture. However, more recent archeology points to a dramatic climate change which could have led to one of the worst droughts in European history –  devastating for a culture that relied heavily on farming.

6. Khmer Empire

The Khmer Empire grew out of the kingdom of Chenla in what is now Cambodia around the 9th century AD and became one of the most powerful empires in Southeast Asia. 

The empire is known to most people as the civilization that built Angkor, Cambodia’s capital city. The Khmer were an incredibly powerful and wealthy culture who were open to several belief systems including Hinduism, Mahayana Buddhism and Theravada Buddhism, which were the empire’s official religions. Their power also included military might as they fought many wars against the Annamese and Chams. 

The decline of the Khmer Empire can be attributed to any combination of several factors. The first being that the empire was ruled by a devarajo or god king, but with introduction of Theravada Buddhism, which teaches self enlightenment, the government was challenged. This led to a lack of a desire to work for the devarajo which impacted the amount of food being produced. During the reign of Jayavarman VII, an elaborate road network was built to make it easier to transport goods and troops throughout the Empire. But some scholars believe that these roads worked against them, making it easier for invaders like the Ayuthaya to get straight to Angkor. 

7. Mycenaeans Civilization

Growing out of the Minoan civilization, the Myceanaeans merged around 1600 BC in southern Greece. Being spread out over two islands and the southern mainland, the Myceaneans built and invaded many major cities like Mycenae, Tiryns, Pylos, Athens, Thebes, Orchomenus, Iolkos and Knossos. 

Many Greek myths are centered around Mycenae including the legend of King Agamemnon, who led the Greek forces during the Trojan War. The Myceaneans were a dominant naval power and used their naval prowess for trade with other nations as well as for military endeavors. Because of a lack of natural resources, the Myceaneans imported many goods and turned them into sellable items and therefore became master craftsmen, known throughout the Aegean for their weapons and jewelry. 

No one knows for sure, but one theory is that unrest between the peasant class and the ruling class led to the end of the Myceaneans. Other point to disruptions in trade routes, or natural factors like earthquakes. But the most popular theory is that they were invaded by a civilization from the north like the Dorians (who settled in the area after the fall of the Myceaneans) or the Sea People (who at the time were migrating from the Balkans to the Middle East). 

8. Aksumite Empire

The Aksumite Empire began in the first century AD in what is now Ethiopia and is believed to be the home of the Queen of Sheba.

Aksum was a major trade center with exports of ivory, agricultural resources and gold being traded throughout the Red Sea trade network and onward to the Roman Empire and east towards India. Because of this, Aksum was a very wealthy society and was the first African culture to issue its own coinage, which in ancient times was a sign of great importance. The most recognizable monuments of Aksum are the stelae, giant carved obelisks that acted as the grave markers of kings and nobles. Early Aksumites worshipped several gods but their main god was called Astar. In 324 AD, King Ezana II was converted to Christianity and from then on Aksum was a zealously Christian culture, and is even allegedly the home of the Ark of the Covenant.

According to local legend, a Jewish Queen named Yodit defeated the Aksumite Empire and burned its churches and literature. However, others believe that southern pagan queen Bani al-Hamwiyah led to the Aksumite decline. Other theories include climate change, trade isolation and over farming leading to starvation. 

9. Nabateans Civilization

The Nabateans were a Semitic culture that inhabited parts of Jordan, Canaan and Arabia from around the sixth century BC. 

They are most widely known as the builders of the city of Petra, which served as their capital. Petra is an impressive city carved out of the cliff side with the crown jewel being the Khazneh, or Treasury, a giant Greek inspired building. The Nabateans’ wealth was gained by being a major stop on a complex trading network, through which they traded ivory, silk, spices, precious metals, gems, incense, sugar perfume and medicine. Because of the extent of the trade route, the Nabatean culture was highly influenced by Hellenistic Greece, Rome, Arabia and Assyria. Unlike other societies of their time, there was no slavery and every member of society contributed in the work duties. 

During the fourth century AD, the Nabateans abandoned Petra and no one really knows why. Archeological evidence proves that their exodus was an organized one that was unrushed, which leads us to believe that they were not driven out of Petra by another culture. The most likely explanation is that when the trade routes they relied on moved north they could no longer sustain their civilization and left Petra behind. 

10. The Olmec 

One of the first Mesoamerican societies, the Olmec inhabited the tropical lowlands of south-central Mexico. The first signs of the Olmec are around 1400 BC in the city of San Lorenzo, the main Olmec settlement which was supported by two other centers, Tenochtitlan and Potrero Nuevo. The Olmec were master builders with each of the major sites containing ceremonial courts, house mounds, large conical pyramids and stone monuments including the colossal head that they are most known for. The Olmec civilization relied heavily on trade, both between different Olmec regions and with other Mesoamerican societies. Because they were one of the earliest and most advanced Mesoamerican cultures at the time, they are often considered the mother culture of many other Mesoamerican cultures. 

Around 400 BC the eastern half of the Olmec’s lands was depopulated- possibly due to environmental changes. They may have also relocated after volcanic activity in the area. Another popular theory is that they were invaded, but no one knows whom the invaders might be.