1. The Indus Valley Civilization
Around 2500 BCE, the Indus Valley people built advanced cities in what is now Pakistan and India. They had plumbing, straight roads, and organized trade, yet we still can’t read their writing.
Why They’re Mysterious:
- Their script remains undeciphered.
- Cities like Mohenjo-Daro and Harappa show advanced urban planning.
- No one knows exactly why the civilization collapsed — maybe climate change or invasions.