If you write on Plato, you should start in medias res. If you write on Thomas Aquinas, you can do the same (unless you are writing for a journal specialising on something completely different, say, business ethics). If you write on a slightly less known author, I would suggest adding at least the dates of birth and death and perhaps a short description of their main work (say “the epistemologist XW (1200–1250)”).
What about writing on South Asian philosophy? If you are writing for a non-specialist journal, you will need to explain a lot, since no one will know even the main authors and schools you will name. Nonetheless, this does not mean that each new piece on South Asian philosophy should resemble a pale summary of scholarhip on X. Even if you need to tell who Jayanta was and what Nyāyā means, this does not mean that you cannot make an original contribution to the debate.

1. Just start with what you discovered. Did Jayanta think that justification is not needed in the case of the “ought” domain? Are you the first one who noticed this move? Be sure that this is your departing point.
2. You can then move to the background needed to appreciate the depth of your discovery. Do not just start with the background, otherwise your reader will think there is nothing new and close your article before reaching its core.
3. Be sure that theme and rheme are well distinguished in your article. The reader should not be confused about what is just a short summary of the background and what is your new and original contribution.
4. Please remember that an article is not a book. You can only convey one point. Don’t try to overdo or you will not manage to convey anything at all.