The Greater One Horned Rhinoceros (rhinoceros unicornis) inhabited the length of north Southasia from east to west, from the Indus plains right across the Ganga-Jamuna doab, along the Ganga maidaan, into the Brahmaputra valley and onward to the Burmese realm. Which means what is today Bangladesh was very much a part of the rhino habitat. About 1600 rhinos are now left in India, in the reserves in Assam, the biggest of which is Kaziranga; and about 400 remain in Nepal's Chitwan and Bardia national parks.
Bangladesh, indeed, has become the most wildlife deficient country in Southasia. The only climax species it can boast of are a handful of Royal Bengal Tigers in the rapidly diminishing Sunderban mangroves. Otherwise, what we have in -this land of teeming humanity is the standard lineup of spotted leopard, Hanuman langur, rhesus macaque, chital deer, and wild boar. Nothing to boast at CITES conclaves about.
Bangladesh's list of 'extinct vertebrae' includes the gaur, the swamp deer (Barasingha), the hog deer, the marsh mugger crocodile, the Gharial crocodile, and the one-horned rhinoceros. (The Lesser Javan Rhinoceros, too, once upon a time, trudged the delta but disappeared even before our local rhino.)
Even a look at the laws show that the rhino is not remote from Bangladeshi history. The Bengal Rhinoceros Preservation Act of 1932 was enacted in a united Bengal, not by the Indian, but by the Bengal government. The Act was superseded only in 1973 when the Bangladesh Wildlife (Preservation) Order was passed, possibly because they saw no hope of a rhino return. That was not very forward looking.