The Olmec, one of the first Mesoamerican societies, it was inhabited in the tropical lowlands of south central Mexico. First signs of the Olmec are around 1400 BC in the city of San Lorenzo. Around 400 BC the eastern half of the Olmec's lands was depopulated possibly due to environmental changes.
The Nabateans were a Semitic culture that inhabited parts of Jordan, Canaan and Arabia from around the sixth century BC. 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. During the fourth century AD, the Nabateans abandoned Petra and no one really knows why
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. The most recognizable monuments of Aksum are the stelae, giant carved obelisks that acted as the grave markers of kings and nobles. According to local legend, a Jewish Queen named Yodit defeated the Aksumite Empire and burned its churches and literature.
Growing out of the Minoan civilization, the Myceanaeans merged around 1600 BC in southern Greece. 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. But the most popular theory is that they were invaded by a civilization from the north like the Dorians or the Sea People.
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. Some scholars believe that these roads worked against them, making it easier for invaders like the Ayuthaya to get straight to Angkor.
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. One of the biggest mysteries of this culture is that every 60 to 80 years they would burn their entire village and reconstruct it on top of the old one.
A prehistoric Native American people, the Clovis culture dates back to 10,000 BC. 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. A theory is that the mammoth and other species became extinct due to over hunting, leaving the Clovis without a viable food source.