Great changes have taken place in the course of some of the rivers in Bengal and the adjoining areas, during the period since 1500 CE.
Although positive evidence is lacking, similar changes can be assumed in the remoter past.
The Teesta River is one of the rivers that has changed over the years.

The Teesta earlier ran due south from Jalpaiguri in three channels, namely, the Karatoya to the east, the Punarbhaba in the west and the Atrai in the centre.
The three channels possibly gave the name to the river as Trisrota "possessed of three streams" which has been shortened to Teesta.
Of these three, the Punarbhaba joined the Mahananda.
The Atrai passing through a vast marshy area known as Chalan Beel joined the Karatoya and the united stream joined the Padma (Ganges) near Jafarganj.
In the destructive floods of 1787, the Teesta river forsook its old channel and rushing south-east it joined the Brahmaputra.
James Rennell made a survey between 1764 and 1777 and his maps are one of the earliest authentic maps of Bengal in existence.
In these maps Teesta is shown as flowing through North Bengal in several branches—Punarbhaba, Atrai, Karatoya, etc.
All these streams combined lower down with the Mahananda, now the westernmost river in North Bengal, and taking the name of Hoorsagar finally discharged into the Ganges at Jafarganj, near modern Goalundo.
The Hoorsagar river still in existence, being the combined outfall of the Baral, a spill channel of the Ganges, the Atrai, the Jamuna or Jamuneswari (not the main Jamuna through which the Brahmaputra now flows), and the Karatoya, but instead of falling into the Ganges, it falls into the main Jamuna, a few miles above its confluence with the Padma at Goalundo.
Great changes have taken place in the course of some of the rivers in Bengal and the adjoining areas, during the period since 1500 CE. Although positive evidence is lacking, similar changes can be assumed in the remoter past. The Teesta River is one of the rivers that has changed over the years.
The Teesta earlier ran due south from Jalpaiguri in three channels, namely, the Karatoya to the east, the Punarbhaba in the west and the Atrai in the centre. The three channels possibly gave the name to the river as Trisrota "possessed of three streams" which has been shortened to Teesta. Of these three, the Punarbhaba joined the Mahananda. The Atrai passing through a vast marshy area known as Chalan Beel joined the Karatoya and the united stream joined the Padma (Ganges) near Jafarganj. In the destructive floods of 1787, the Teesta river forsook its old channel and rushing south-east it joined the Brahmaputra.James Rennell made a survey between 1764 and 1777 and his maps are one of the earliest authentic maps of Bengal in existence. In these maps Teesta is shown as flowing through North Bengal in several branches—Punarbhaba, Atrai, Karatoya, etc. All these streams combined lower down with the Mahananda, now the westernmost river in North Bengal, and taking the name of Hoorsagar finally discharged into the Ganges at Jafarganj, near modern Goalundo. The Hoorsagar river still in existence, being the combined outfall of the Baral, a spill channel of the Ganges, the Atrai, the Jamuna or Jamuneswari (not the main Jamuna through which the Brahmaputra now flows), and the Karatoya, but instead of falling into the Ganges, it falls into the main Jamuna, a few miles above its confluence with the Padma at Goalundo.
Teesta River