I'm not sure any of the Just-so Stories qualify as historical. The ones that purport to take place in Africa (and I can only think of two or three in the whole book) are distinctly ahistorical, being mythical tales of how natural phenomena came to be.

Kim might be an interesting work of Kipling's to discuss, in a unit on the British in India, although strictly speaking it is not historical. (I mean, it's old, but he wasn't writing an historical novel when he wrote it.)