Short answers, pulled from the story.
The Neolithic site named Mehrgarh emerged in Balochistan province of Pakistan around 7000 BCE. This mountain settlement provided new insights into how farming and herding began in South Asia before communities transformed into large urban centers by 2600 BCE.
Mohenjo-daro covered more than 250 hectares within the lower Indus plain and featured world-first known city sanitation systems with covered drains lining major streets. Individual homes obtained water from wells while waste water was directed to these drainage networks, creating a unique urban layout that opened only to inner courtyards and smaller lanes.
Charles Masson traveled through Punjab in 1829 gathering intelligence for the East India Company and made notes on Harappa's artifacts lying half-buried in the ground. Systematic excavations began at Mohenjo-daro in 1924-25 after John Marshall directed ASI excavations starting in the 1920s following Lord Curzon's Ancient Monuments Preservation Act 1904.
Maritime trade networks operated between Harappan and Mesopotamian civilizations as early as middle Harappan Phase with evidence reaching Oman peninsula Bahrain southern Mesopotamia and even Nile River valley Anatolia Caucasus. Plank-built watercraft equipped with single central mast supporting sail woven rushes or cloth enabled sea-borne trade handled by merchants from Dilmun modern Bahrain Eastern Arabia and Failaka via Persian Gulf routes.
Between four hundred and six hundred distinct Indus symbols have been found on stamp seals small tablets ceramic pots and over dozen other materials including signboard hanging over gate of inner citadel at Dholavira. Finnish Indologist Asko Parpola concludes uniformity precludes possibility widely different languages being used suggesting early form Dravidian language must have been language of people.
Around 1900 BCE signs gradual decline began emerging by around 1700 BCE most cities abandoned due to climate change possibly due abrupt critical mega-drought cooling four thousand years ago marks onset Meghalayan Age present stage Holocene. Ghaggar-Hakra system rain-fed water-supply depended monsoons grew significantly cooler drier from about 1800 BCE linked general weakening monsoon time leading aridification that reduced water supply enough cause civilisation demise scatter population eastward toward Ganges basin.