Rabindranath Tagore holds several historical distinctions. Often cited is the fact that his father was instrumental in spreading a Hindi sect that helped change the way the religion was practiced in contemporary India. Another common factoid is that Tagore was the first writer to win a Nobel Prize in Literature who did not write in English. But perhaps the most historically significant aspect of Tagore's biography is his complicated relationship with the development of a modern Indian identity.
Tagore is often credited with revitalizing Bengali-language literature—not just making by innovations in the way that the language was written in poetry and prose, but also by elevating the region's literature to be comparable with other literatures on a world stage. Tagore helped the Bengal ethnic group, in turn, define an identity at a moment when the Indian subcontinent was treating as a more or less homogenous colonial outpost of the British.
But Tagore was disinterested in any sort of identity-based nationalist project, and he seemed to bristle at both comparisons to his Bengali contemporaries and to the idea that ethnicity or place should form the basis of politics. This may seem paradoxical, given the fact that Tagore was an ardent critic of the British imperial regime. Famously, he was knighted by the British crown in 1915 for his contributions to literature, but returned that knighthood in 1919 following an incident known as the Jallianwala Bagh Massacre when British imperial soldiers murdered a slew of unarmed Punjabi civilians during a peaceful protest.
Tagore was also a close friend of the Indian liberation leader Mohandas Gandhi, but never joined in Gandhi's campaign to win India's independence from the British crown. Surely Tagore was sympathetic to Gandhi's aims, but Tagore, again, was staunchly anti-nationalist, and clearly disagreed with Gandhi about the need to appeal to a kind of Indian national identity in the name of winning such liberation.
Don't forget, the Indian subcontinent is massive, and houses all manner of ethnic groups. The Bengals themselves would break off from Pakistan and form their own nation of Bangladesh in 1972. By then, Tagore had long since passed, so this is not to suggest he had any hand in Bangladesh's independence, or would have even particularly rooted for it.
Tagore was an idiosyncratic individual at a historically precipitous moment when the British crown was losing its grip on its empire amongst two world wars. Tagore both took issue with the occupiers, yet was skeptical of any sort of politics built on ethnic bonds. If you are trying to figure out what to make of this, just take a look at the egalitarian style of Tagore's short fiction. He focuses on all manner of people, regardless of class, gender, or origin, and his pen treats them all equally as complex humans living difficult lives. Tagore rarely even names the caste that his characters come from. He clearly didn't see people as naturally divided into any sort of category, but united in the simple fact of their strange existences.