Mohenjo Daro and Harappa were the two main cities of the Indus Valley civilization in India, or more exactly in present-day Pakistan. Take a tour with this video.

This civilization preceded those of Egypt and Mesopotamia before disappearing around 1500 BC. The cause of this disappearance seems to be a soil become unfit for cultivation. The town of Mohenjo Daro was abandoned, and the site was repopulated centuries later.
During excavations by archaeologists in the 1920s, 37 skeletons, often incomplete, were uncovered. According to some authors and websites, scientists have measured a radioactivity level 50 times higher than normal in these skeletons. This proves beyond doubt that the city was destroyed by a nuclear weapon -or so they say!
Example :

source
As a reminder, in fact only 37 bodies were found. This was at least the case in 1964, see the first link given at the bottom of the page. 37 dead bodies is surprisingly few for a disaster of such a magnitude, since we are talking about an entire city that would have been the target, but let’s forget this “detail”...
So I decided to look for the source of this information, which brings me to the case of the “archaeologist” A. Gorbovsky.
A. Gorbovsky
Here is Alexander Gorbovsky’s profile (1930-2003). He does not seem to have been an archaeologist, but rather a writer and historian, with a clear attraction for science-fiction and “alternative” history. His writings are about how to win the lottery by the power of thought, man has lived side by side with dinosaurs, the phenomenon of poltergeists, the art of divination, the antediluvian civilizations, etc etc ...
His book Riddles of ancient history, published in 1965, does not seem to exist under this English title, but we find the original version in Russian ЗАГАДКИ ДРЕВНЕЙШЕЙ ИСТОРИИ. This book deals with “mysteries” of human history, such as Incas and a race of giants, and various disasters.

Since this reference is so often cited, one would expect solid arguments. But the passage about Mohenjo Daro is surprisingly short (page 162):

There are some other finds that also surprise the investigator. In this regard, one is reminded of the find of a human skeleton in India, which radioactivity was 50 times higher than normal! (ref. "Problems of Space Biology", vol. II, p.23). The deposits that were found in the skeleton could only have had such a high radioactivity if this person, who died 4,000 years ago, had eaten food, which contained radioactivity hundred of times higher than normal.
We learn that one (and only one) radioactive skeleton has been discovered somewhere in India. It is 4000 years old, while the alleged nuclear disaster of Mohenjo Daro is 3500 years old. Why not ... A dating can sometimes lack precision.
Luckily, mention is made of the article Problems of Space Biology.
Alexander V. Lebedinsky
The exact title is Problems of radiation safety in cosmic flights by A.V. Lebedinsky and Yu. G. Nefedov. Problems of Space Biology also exists, but it is an incomplete English translation for the Nasa from 1971. This is a 1962 Russian scientific article that addresses the possible risks to humans in a space environment.
We can find this on page 23 and 24:

People are exposed to the influence of penetrating radiation also on Earth (vs space).
For example, in the regions of monazite sands in India containing thorium, the total dose of irradiation reaches 600 mrem/year. Increasing of natural level of radiation is observed also in the high mountains regions where the dose of irradiation may be 2-3 times higher than the dose at the sea level. At this point of view the data of paleoradiobiology are of large interest. According to recently received data from Mayneord, in the ribs of a man who lived 4000 years ago the radioactivity was approximately 50 times higher than in modern man. (3.4.10 -12 and 6.8.10 -14 curie/gr. respectively)
This requires some explanation; the context is space flights. The first paragraph deals with natural radioactivity in India, where the soil sometimes contains a lot of monazite sand containing thorium; this is particularly the case in the region of Kerala. When you gain altitude, this radioactivity increases.
Curie is the old radioactivity measurement unit. Nowadays we use becquerel.
W.V. Mayneord
William Valentine Mayneord (1902-1988) was a British researcher in medical physics. He was very interested in radioactivity, especially its consequences on human body. The citation comes from a report from 1960: Hazards of Nuclear and Allied Radiation p. 73-74, and concerns the differences in radioactivity for bodies subjected to natural radioactivity.

We can read that while W.V. Mayneord has actually analyzed a 4000 years old bone, it is in fact an Egyptian bone, not an Indian one, and its radioactivity is identical that of the present-day man. Not 50 times more, even not 50% more. We find the same value of 0.34.10-12c/g which is just another way to write 0.34 µµc/g. The funny fact is that this Egyptian had in his bones a radioactivity lower than that of a Londoner or an Eskimo.
I could not find where the value of 6.8.10-14 comes from, but that is absolutely not consistent with what Mayneord writes. Lebedinsky was wrong, and this mistake was unfortunately taken over by Gorbovsky who did not check the information.
Conclusion: The myth of radioactive skeletons found in Mohenjo Daro is not based on any valid evidence:
• There are not many but only one skeleton.
• This skeleton is Egyptian and not Indian.
• Its radioactivity is absolutely normal.
More reading :
– An article from 1964, so maybe not up to date, but nevertheless interesting, explaining the history of the site and the alleged origin of the bodies found:
https://www.penn.museum/sites/expedition/the-mythical-massacre-at-mohenjo-daro/
– An analysis of Von Daniken’s statements in Chariots of the Gods, and of other writers’, concerning the Vedic writings in the Mahabharata, clearly showing that these authors have falsified the original text to make it correspond to their theories:
http://www.jasoncolavito.com/uploads/3/7/5/9/3759274/colavito_-_ancient_atom_bombs.pdf