It depends on how exactly you classify human species, but right now it's looking like around 100,000 - 50,000 years ago or so there were at least 5 human species concurrently. Us, Neandertals, Denisovans,Homo Floresiensis (hobbit people), Luzonensis. There are quite a few additional that are unclear/subject to debate. Denisovans are apparently divided again into 3 different populations. It all gets really fuzzy though; they've found one individual who is first generation Neandertal and Denisovan, (one parent from one group, the other from the other). They could hybridize with each other and with us (and did).