They were believed extinct after the Asgardians stopped an attempt to do that five thousand years ago , but unbeknownst to the Asgardians , Malekith and a number of warriors escaped and went into stasis until another attempt would be possible .
They were believed extinct after the Asgardians stopped an attempt to do that five thousand years ago . 
 Unbeknownst to the Asgardians , Malekith and a number of warriors escaped and went into stasis until another attempt would be possible .