Nuclear war.
The Thar Desert is probably the most densely populated desert on earth.
Mankind has been present in India since prehistoric times. Cave art there dates back that far. But he was probably nomadic for a long period before the first permanent settlements appeared there, which records indicate were almost 10,000 years ago. Need a link? Got one for ya to our friends at Wikipedia, where knowledge is free.
Lots of things, but the answer you are probably looking for is that they are all landlocked.
I don't know exactly what they learned, but I do know that they probably had teachers called Gurus that stayed with them until they were twenty. Until then, the student may have had to do chores for them. Also, the gurus probably taught, if not, included government and religion in their studies.
Some seals were used as name tags, and guards at city gates would not let people in unless they had one. Other Harappan seals were used to stamp the word 'namana' (greetings) on lettterhead. Another sort of stamp seal was used in freightyards and warehouses to stamp addresses on cargo, these seals had names of towns, rivers and countries on them. Visit 'Indus Script Dictionary' on Facebook to see many photos of Harappan seals.
Probably for the same reasons we have bathrooms and indoor plumbing.
There are various opinions as to what happened to the Indus valley civilization. Probably them most held is that climate change (disappearance of the monsoons) resulted in a migration to the east but in smaller more isolated towns.
The civilization probably had economic specialization. The civilization probably had social stratification.
The Anasazi lived on the inside of a canyon, so they probably didn't have easy access to food. They were also a peaceful people, so they could have easily been defeated in battle.
Which civilization?
The language spoken by the Indus Valley civilization is unknown as their script has not been deciphered. Archaeologists have not been able to definitively determine the language they spoke based on the limited written records found.
He's been missing for 30 years. He dissapeared at age six which probably would mean he'd be a grandpa by now if he wasn't missing.
The Nile.
The Olmec civilization is believed to have influenced later civilizations in Mesoamerica through their art, architecture, and religious practices. Their monumental stone heads and ceremonial centers may have set the precedent for future urban planning and sacred spaces. Additionally, their agricultural techniques and trade networks likely had a lasting impact on the region's economy and social structure.
Maybe and probably CHINA
They were probably nomadic family groups.
The ancient Chines civilization was probably developed by neolithic ancestors of the Chinese who lived along the Yellow River.