Indus Valley Civilisation is a network of urban settlements, that stretched across North Western India, Pakistan, parts of Afghanistan which existed between 3500BCE and 1700BCE. Foundations to the civilisation were laid way before 7000BCE.

It's a bronze age civilisation, meaning people mainly used bronze along with other copper alloys to make their metal tools. It's one of the earliest bronze age civilisations, others being Egyptian, Mesopotamian. All three of them had trade relations with each other.

It was named Indus Valley Civilisation by John Marshall, who was Director General of Archaeological Survey of India from 1902-1928. John Marshall discovered the city of Harappa. He initiated and oversaw the excavations at Harappa and MohenjoDaro starting from 1920. He is a key figure in the discovery, excavation and analysis of Indus Valley Civilisation. He called it the Indus Valley Civilisation, as Harappa and MohenjoDaro first cities to be discovered were found on the plains of Indus River system. It's also called the Harappan Civilisation as per the naming convention in archaeology to name a civilisation after its first city to be found and Harappa was the first city to be discovered and excavated.

As we embark on the journey of learning about Indus Valley Civilisation, it is helpful to first be familiar with the timeline of Harappan Civilisation and timeline of human migration into South Asia.

70000 years ago - Modern humans (Homo Sapiens) migrate Out of Africa

65000 years ago - The Out of Africa migrants reach India

45000 - 20000 years ago - Descendants of Out of Africa migrants, called the First Indians begin using microlithic technology

7000BCE - Rise of an agricultural settlement in Mehrgarh, a village in Balochistan of Pakistan

7000 - 3000BCE - Agriculturalists from Zagros mountains of Iran migrate to India

7000 - 2600BCE - Cultivation of barley, wheat and increase in consumption of domesticated animals in Mehrgarh.

5500 - 2600BCE - The Early Harappan Era, early agricultural settlements turn into towns.

2600 - 1900BCE - The mature Harappan period, increased urbanisation with emergence of cities, increase in trade overseas, unprecedented level of standardisation across the Indus realm with respect to script, seals, motifs and weights.

2500 - 1300BCE - Climate change globally that lasted a millenium.

2300 - 1700BCE - Period of civilisation of Bactria-Margiana Archaeological Complex(BMAC), centred on the Oxus river spread over contiguous parts of today's Afghanistan, Uzbekistan and Tajikistan.

2100BCE - Kazakh steppe pastoralists migrate south to Central Asia.

2000 - 1000BCE - Multiple waves of steppe pastoralist migrants, native speakers of Indo European languages from Central Asia move into South Asia throughout the whole millenium.

1900 - 1300BCE - The late Harappan period, Harappan Civilisation declines with the collapse of cities, trade overseas and decline in script usage.

1800BCE - Trade between Mesopotamia and Indus valley collapse.

1500 - 500BCE - Composition of Rigveda, followed by other Vedic literature in Sanskrit.

1300BCE - People abandon Harappa.

300BCE - 400AD - Composition of Hindu epics Ramayana and Mahabharata.

1920 - Indus Valley Civilisation discovered, excavation begins.

1947 - Partition of India into India and Pakistan, partition of Indus Valley sites between the countries.