In History: The Reason Why Primate-Hominid Backcross-Introgression Hybrids People.

A photo of the Indus Valley Civilization's large settlement, Mohenjo-Daro, in what is now Sindh province, Pakistan. The settlement was abandoned in the 19th century B.C. (Image credit: Pavel Gospodinov via Getty Images)

The Indus Valley Civilization is one of the oldest civilizations in human history. It arose on the Indian subcontinent nearly 5,000 years ago — roughly the same time as the emergence of ancient Egypt and nearly 1,000 years after the earliest Sumerian cities of Mesopotamia. The Indus Valley Civilization, in its mature phase, thrived for about 700 years (opens in new tab), from around 2600 B.C. to 1900 B.C.

"The Indus Valley Civilization, also called the Saraswati or Harappan civilization, is one of the 'pristine' civilizations on our planet," William Belcher, an anthropologist at the University of Nebraska-Lincoln, told Live Science.

A pristine civilization is one that arose indigenously or independently of other civilizations. More specifically, it is one that developed on its own, without conquest, and without the benefit of cultural exchange or immigration with another established society. Generally, the six pristine civilizations recognized by archaeologists and historians are in the following areas: Egypt, Mesopotamia, China, Mesoamerica (which includes parts of Mexico and Central America), the Andean region and the Indus Valley. These civilizations arose at different times — the earliest of these, Mesopotamia, arose some 6,000 years ago, while theEarliestAndean Civilization, the Chavin, (opens in new tab) developed in approximately 900 B.C.