Álfheimr - or Alfheim - is one of the nine realms. The others are Hel, Jotunheim, Midgard (and Asgard, they're together now), Muspelheim, Svartalfheim, Niflheim and Vanaheim. As it stands right now, there is a delicate peace and balance that allows all the realms to exist in harmony. That peace is maintained by offerings to maintain those treaties. Upsetting those treaties may bring disaster on any of the realms.
I'm not entirely sure what brought us here wasn't the result of some discord between the realms.