It's not foreign. It's Indian. Also it's there for long.
It's Bengali/Bangla.
It's also the same language spoken by Bangladeshi, though with a little different accent.
It's the second most widely spoken of the 22 scheduled languages of India, behind Hindi and the official and most widely spoken language of Bangladesh. It's also the 5th most widely spoken language worldwide, whereas Hindi is in 6th.
India's national anthem 'Jana Gana Mana' is in Bengali, was written by nobel laureate Rabindranath Tagore.