Where to find lvl 38-40 mobs?

[Tallenn]

40-50 is hard without Kunark. Limited number of mobs compared to numbers of people trying to kill them. Here's one that many people don't think of, though it probably shouldn't be attempted without a group:
bears, wolves, and spiders in Permafrost in the area under the pits leading to Vox's chamber.

Take comfort in the fact that you likely have several months to make it to 50 before Kunark hits...