Editing Brahmaputra River (section)

===Earlier history===
The [[Bodo-Kachari|Kachari]] group called the river "Dilao", "Tilao".<ref>{{Cite book|last1=Syed|first1=Dr. M.H|last2=Bright|first2=P.S|url=https://books.google.com/books?id=reuQbFK9Rz4C|title=Assam General Knowledge|publisher=Bright Publications |isbn=9788171994519|access-date=31 December 2020|archive-date=8 October 2021|archive-url=https://web.archive.org/web/20211008075845/https://books.google.com/books?id=reuQbFK9Rz4C|url-status=live}}</ref> Early Greek accounts of Curtius and Strabo give its name as Dyardanes ([[Ancient greek]] Δυαρδάνης) and Oidanes.<ref>{{Cite book|last1=Burnell|first1=A. C.|url=https://books.google.com/books?id=LMbADwAAQBAJ&pg=PA132|title=Hobson-Jobson: Glossary of Colloquial Anglo-Indian Words And Phrases|last2=Yule|first2=Henry|date=24 October 2018|publisher=Routledge|isbn=978-1-136-60332-7|pages=132|language=en|access-date=25 November 2020|archive-date=8 October 2021|archive-url=https://web.archive.org/web/20211008075846/https://books.google.com/books?id=LMbADwAAQBAJ&pg=PA132|url-status=live}}</ref> In the past, the course of the lower Brahmaputra was different and passed through the [[Jamalpur District|Jamalpur]] and [[Mymensingh]] districts. Some water still flows through that course, now called the Old Brahmaputra, as a distributary of the main channel.

A question about the river system in [[Bangladesh]] is when and why the Brahmaputra changed its main course, at the site of the Jamuna and the "Old Brahmaputra" fork that can be seen by comparing modern maps to historic maps before the 1800s.<ref>e.g. Rennell, 1776; Rennel, 1787</ref> The Brahmaputra likely flowed directly south along its present main channel for much of the time since the [[last glacial maximum]], switching back and forth between the two courses several times throughout the [[Holocene]].

One idea about the most recent [[avulsion (river)|avulsion]] is that the change in the course of the main waters of the Brahmaputra took place suddenly in 1787, the year of the heavy flooding of the river Tista.

In the middle of the 18th century, at least three fair-sized streams flowed between the [[Rajshahi]] and [[Dhaka]] Divisions, viz., the Daokoba, a branch of the Tista, the Monash or Konai, and the Salangi. The Lahajang and the Elengjany were also important rivers. In Renault's time, the Brahmaputra as a first step towards securing a more direct course to the sea by leaving the Mahdupur Jungle to the east began to send a considerable volume of water down the Jinai or Jabuna from Jamalpur into the [[Monash (river)|Monash]] and Salangi. These rivers gradually coalesced and kept shifting to the west till they met the Daokoba, which was showing an equally rapid tendency to cut towards the east. The junction of these rivers gave the Brahmaputra a course worthy of her immense power, and the rivers to right and left silted up. In Renault's Altas they very much resemble the rivers of Jessore, which dried up after the hundred-mouthed Ganga had cut her new channel to join the Meghna at the south of the [[Munshiganj]] subdivision.

In 1809, [[Francis Buchanan-Hamilton]] wrote that the new channel between Bhawanipur and Dewanranj "was scarcely inferior to the mighty river, and threatens to sweep away the intermediate country". By 1830, the old channel had been reduced to its present insignificance. It was navigable by country boats throughout the year and by launches only during rains, but at the point as low as Jamalpur it was formidable throughout the cold weather. Similar was the position for two or three months just below Mymensingh also.