This is technical (mathematical) writing. I think what was intended is:
The set of maps referred to can be identified with the tangent space.
This is standard mathematicalese.
Notice that maps referred to, although it ends with a preposition, sounds better than referred maps; the latter sounds a little off. But better would be to drop the referred, and if necessary, give the name of, or the symbol representing, the set of maps appositively, thus,
The set of maps, $symbol$, can be identified with the tangent space.
This is more natural mathematicalese.
However, because of the plural in tangent spaces, the following might have been intended:
The sets of maps referred to can be identified with tangent spaces.
The set of maps referred to can be identified with (the union of) tangent spaces.
The comment about dropping referred can be applied in these cases too. To be definitive, we would need more context.
Without set[s] of, the statement is sloppy, since although mathematicians will interpret it as the set of such maps, it is not the maps themselves which are identified with the tangent space (if that was intended), but merely with elements of the tangent space ...; this is a frequent source of obscurity in mathematical writing.
I don't think it is appropriate for those who are unfamiliar with mathematical writing to comment on this question.