Mohenjo-daro

Mohenjo-daro is an archeological site of one of the largest Indus Valley cities, which thrived around 2000 BCE. Pseudohistorians and proponents of ancient advanced civilizations or extraterrestrial visitations claim that there is evidence that its population was killed off by an atomic bomb explosion around 1500 BCE. The proffered evidence is rife with pseudoscience; so, unsurprisingly, it has been featured prominently on the History Channel's show Ancient Aliens.

Mud brick buildings
One difficulty with the nuclear blast claim at Mohenjo-daro is immediately apparent when photographs of the dig site are examined. The buildings were made with kiln-fired mud bricks. Some of the walls are still 15 feet high. How an unreinforced mud brick wall withstands a nuclear blast never seems to be addressed.

Bodies
The primary evidence cited in support of an atomic bomb explosion at Mohenjo-daro is the discovery of a series of bodies throughout the cities. Their presence, it is argued, suggests a single cataclysmic event: when excavations of Harappa and Mohenjo-Daro reached the street level, they discovered skeletons scattered about the cities, many holding hands and sprawling in the streets as if some instant, horrible doom had killed its inhabitants. People were just lying, unburied, in the streets of the city; there seemed no-one available to bury them afterwards. The actual evidence however, is far different, more subtle and more interesting. The bodies were discovered during excavations between 1922-1931. Scholars have criticized the approach used during the dig period and have stated that the poor methodology makes interpretation difficult. However, even though some of the original excavators interpreted the evidence in a way that suggested the bodies were linked by a single catastrophic event, they took the view that the catastrophe was a war and not a nuclear explosion.

A total of thirty-seven bodies were found. Although some were found in the same parts of the city, their distribution suggested that many came from different time periods. Mohenjo-daro had three major periods: Early, Intermediate and Late. Some of the bodies were clearly Early period and some clearly Late. The two periods are a thousand or more years apart. Another key point is that the bodies actually showed clear signs of burial. The most infamous group of bodies, as highlighted from the quote above, that were found laying in the middle of the street were buried during the Late period, when buildings had been built over constructions from earlier periods. The bodies were buried above a road from hundreds of years earlier.

Proponents of the bomb explosion often like to point to the preservation of the bodies, particularly the lack of signs of scavengers as proof that something like elevated background radiation kept animals away. One important point against this is that this is one of the driest and hottest spots on the planet, perfect for preservation. The scavenger problem is only a problem for the pseudohistorians who seem unaware that the bodies were actually buried. Small groups of bodies dating from multiple periods a thousand years apart, with clear signs of burial, and some stratum coincidences, clearly is weak evidence for an atomic explosion. The evidence is also nothing like what is presented on proponent websites or television. An interesting fact though is that this is not the first time that the Mohenjo-daro bodies were the subject of controversy. The original excavators tried to use them as proof that the Indus valley civilization was killed by invading hordes of Aryans. Much of the evidence presented showing that the bodies were not due to a single large-scale event was elucidated 50 years ago to disprove the invading horde hypothesis.

Radioactivity
Beyond the bodies themselves pseudohistorians make a series of claims about radioactivity levels in the area. These claims range from a radioactive dust covering the whole city, to the bodies themselves being "among the most radioactive ever found, on par with those at Hiroshima and Nagasaki." The problem with these claims is that they are so vaguely sourced it's impossible to find the original claims to verify it.

Vitrification
One common claim is that the sand around the city had vitrified similar to the Trinity Site in New Mexico. However, what was actually found was the dumping ground for broken pots that were often made by vitrifying sand in a kiln.

What really happened
Though the Indus Valley civilization may not have deployed nuclear weapons, it is arguable that, in other ways, they were the most advanced civilization of their day by far. For example, we don't really have any evidence the Indus built pyramids or ziggurats like the contemporary Egyptians or Mesopotamians - archeologists have found no definitive Indus Valley civilization temples. Rather, the Indus people spent their time and energy building and inventing things like covered sewers and flush toilets, hierarchical grid-planned cities with paved roads, effectively universal access to water, an octal-decimal metric system, and even the assembly line.

Though the Indus people had arms, they most likely used them for defense against raiders, and no conclusive evidence of military aggression has been shown for the Indus Valley civilization, which thus appears to have achieved one of the longest periods of peace in the history of human civilization.

Though the Indus script remains undeciphered, its ubiquity in both place (a text has been found as far away as Somalia!) and usage points to a level of literacy among the Indus far higher than in all other societies existing in the Third millennium BCE.