The ruins of two ancient cities, Harappa and Mohenjo-Daro (both in modern-day Pakistan), and the remnants of many other settlements, have revealed great clues to this mystery. Harappa was, in fact, such a rich discovery that the Indus Valley Civilization is also called the Harappan civilization.
The first artifact uncovered in Harappa was a unique stone seal carved with a unicorn and an inscription. Similar seals with different animal symbols and writings have since been found throughout the region. Although the writing has not yet been deciphered, the evidence suggests they belonged to the same language system. Apparently, Mesopotamia's cuneiform system had some competition in the race for the world's first script.
The discovery of the seals prompted archaeologists to dig further. Amazing urban architecture was soon uncovered across the valley and into the western plains. The findings clearly show that Harappan societies were well organized and very sanitary.

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