Harappa Culture (a.k.a.: Indus Valley Civilization):

Major excavations at Mohenjo-Daro (Mount of the Dead) and Harappa since 1926 CE

• Cities in existence since 2750 BCE, or earlier
• Early writing system, not yet reliably deciphered, possibly related to southern Indian (Dravidian) languages.
• Cities highly organized / planned (rectangular streets, bath at center)
• elaborate system of drainage and sewers
• Mohenjo - Daro features "Great Bath," [39 x 23 x 10 ft.] possibly used for religious ritual.
• Other excavations point to fire altars and brick platforms (possibly for animal sacrifices)

Images / Figurines:

• Female figures, often with elaborate headdress (sign of divinity)
• Male figurines, oftentimes in cross-legged (later yogic) seating position , again with elaborate headdress.
• Stones with phallic images (reminiscent of lingam)

Other images recovered:

• animal figurines (bulls, elephants, etc.)
• prominence of certain trees
• number seven prominent

Period of decline:

Decline of the Harappan culture from 1750 BCE onwards (or earlier?)

Migration of Indo-Europeans into Indian subcontinent from 1750 BCE onwards.

Different explanations for decline: Invasion theory; possible drastic change of course of Indus river, leading to extensive flooding; possibly an epidemic reduces population drastically; etc...