Short answers, pulled from the story.
The Indus River begins as a perennial spring known as Sengge Zangbo or the Lion's Mouth located in the high Tibetan plateau near the sacred Mount Kailash. This source flows year-round and feeds a river that eventually carves a path through some of the most rugged terrain on Earth.
The Indus Valley Civilization flourished from 3300 BC to 1900 BC with major cities including Harappa and Mohenjo-daro. Over 1,052 other settlements rose along its banks creating a sophisticated network of trade and governance that stretched from northeast Afghanistan to the coast of modern-day Gujarat.
The Persian Empire under Darius the Great was the first West Eurasian empire to annex the valley followed by the Macedonian armies of Alexander the Great. Subsequent empires including the Mauryan and Kushan Empires and Muslim armies led by Muhammad ibn al-Qasim, Mahmud of Ghazni, and Babur crossed the river to invade Sindh and Punjab.
The five major tributaries are the Jhelum, Chenab, Ravi, Beas, and Sutlej which converge to create the Panjnad River. This Panjnad River joins the Indus at Mithankot after the river was sometimes known as the Satnad River or seven rivers.
Only about 1,816 individuals of the Indus River dolphin remain as this subspecies is found nowhere else on Earth. These endangered cetaceans face threats from habitat degradation caused by the construction of dams and canals, entanglement in fishing gear, and industrial water pollution.
Experts warn that once the glaciers of the Tibetan Plateau vanish, water supplies in Pakistan will be in peril potentially reducing river flows by as much as 50 percent. The Indus Basin Irrigation System developed over the past 140 years has already reduced the river's flow and increased soil salinization rendering some farmland useless for cultivation.