Simplify the following text for a Grade 9 native English-speaking person.
Original: Northern Indian subcontinent : Bhutan ( almost extinct ) , Bangladesh ( close to extinction ) , India ( present in small numbers and increasing ) , Myanmar ( possibly extinct ) , Nepal , Pakistan ( close to extinction ) . Usually found in the river systems of Indus ( Pakistan ) and the Brahmaputra ( Bangladesh , Bhutan & North eastern India ) , the Ganges ( Bangladesh , India & Nepal ) , and the Mahanadi ( in the rainforest biome ) ( India ) , with small numbers in Kaladan and the Ayeyarwady River in Myanmar .
Simplified: They are extinct in Pakistan 's Indus River , in the Brahmaputra of Bhutan and Bangladesh and in the Irrawaddy River in Myanmar .