The relations between humans and necromancy change from region to region and time to time but there is something that makes things more complex, this is the same nature of necromancy.
This kind of magic appeared the first time living became interested in dead and believed that they could contact with them somehow.
On the other side though necromancers were believed to be all powerful, many times they were not accepted by the society. This because though humans were in need of their powers they couldn't accept those of their rituals had to do with human corpses. What made them even more terrifying was that they had the power of cursing. Most of their curses are known to bring horrible death.
The above of course do not stand in all cases, in some of them necromancers where accepted as respectable persons and had considerable positions in their tribes