This chapter recounts the birth of a river and growth of a floodplain. Drawing from the geological, hydrological, and biological sciences and other similar works, the chapter narrates the river’s early geological history, the life and times of its waters, sands, soils, climate, monsoon, etc. While recounting these dynamics of the river, the chapter asks questions such as: Where do the Brahmaputra’s waters arise from? How does the sand move? Is the life on the land surrounding the river dependent on the latter? What happens when the river receives more water than it can carry? The chapter claims that an understanding of this deep history of the river is essential for a sense of the long, turbulent times the river has undergone and will experience in the future.