Literary history (and with that, the historicity of literature) is a fiction. That's from Annette Kolodny's famous essay "Dancing Through the Minefield."
A field itself is a fictional way of segmenting reality. Take Spanish literature. Please, take it.
It could be the literature of a nation state, Spain.
You could study Spanish literature as part of "Romance philology," European Studies, Comparative Literature, Mediterranean Studies, Hispanic Studies, world literature, Transatlantic studies, Iberian studies; or you could segment it into Andalusian studies, Castilla / León studies... You could see Catalan studies as part of a larger Iberian studies, or as part of European or Mediterranean studies.
You study it segments of it as part of women's literature, the history of drama. You would usually segment it into time periods, like medieval, early modern, twentieth century...
You could argue why some of these frames are more useful or fruitful or interesting or politically justified than others. Why study Spain apart from Portugal when you could study Iberian studies as an organic whole? Why separate the study of Spain from that of Latin America? Why take Arabic Spain as a separate object of study from Christian Spain? What you can't argue, I think, is that any of these options is simply "given" or inevitable. You can take geographical unity or proximity, language, genre, gender, or anything else as the criterion for marking the boundary of a field.
That's even without problematizing the notion of literature and culture themselves.
Latin American and Spanish American studies has the advantage of already including more than one nation state and region. So the nation and state are significant (Hugo Chavez has just died.) But only very specialized courses in the US are devoted just to Venezuela, or Mexico, or Argentina. Between Latin American and Spanish American, the only difference is whether Brazil is included or excluded. So here are two contiguous or overlapping fields.
So where does history come in? I believe the historicity of literature is more than a fiction. Kolodny is imprecise in her wording. What is historical, though, is the way in which literary history has been written. In other words, it should be possible to write a rigorous history of such fictions.