In Western folklore, dragons are usually portrayed as evil. This is in contrast to Asian dragons, who are traditionally depicted as more benevolent creatures. Many modern stories represent dragons as extremely intelligent creatures who can talk, associated with powerful magic. Dragons have also been shown as guardians and friends of humans, with evil dragons simply misunderstood by humans. In stories a dragon's blood often has magical properties: for example in the opera Siegfried it let Siegfried understand the language of the Forest Bird. The typical dragon protects a cavern or castle filled with gold and treasure.