Kanglus forget, we have one ace in the hole to protect territorial conquest of chickens neck at time of war, a tactic many, MANY armies in the past have used in many many cultures for defence : river diversion.
It will take Indian army a grand total of maybe six hours to find enough stone and concrete to divert the teesta south of jalpaiguri. Game over. thank you for coming, now the rear of you is flooded marshland and all of your troops are stuck and we kill them like fish in a barrel.
Kanglus do not realize that they are at an extremely severe geopolitical disadvantage to India and needling India will be a form of self harming suicide, given that India's ability to hurt kangaaldesh is far more than kangaaaldesh trying to bring up phantom of Bengal Sultanate.
FYI, Bengal Sultanate was an absolute joke of a military power. It didnt just lose to british, Bengal Sultanate keeps losing to whomever is ruler of Delhi/Jaunpur area throughout its intermittent existence at times of weakness at Delhi darbar.
I cant think of very many battles Bengal Sultanate won against Dilli or Jaunpur fyi. They almost always got whacked when they came Bengal sultanate's way and pretty much is a good example of local seperatism during centralised weakness but not a grand military power of its own.
Kangulus also forget, India has air dominance over Bengal. And Bengal has a humongous weakness evident from Pal empire's period ( and it instrumental to its fall) : bengal sucks for quick mobilisation INSIDE bengal, because Bengal has like almost as much rivers (if you count the individual dharas of ganga-brahmpauptra-meghna etc as rivers) than rest of India combined. Meaning, if you want your army to go somewhere in bengal/assemble, your army has to cross 10 times as much rivers as any other army in India. Which, in modern times, means ' you blow up bridges across bengal, bengal army is fooked trying to cover bengal'.
game over.