Not much information was given by the sailor who appeared to have become insane. During his final days he spoke in riddles and nonsense, sometimes in an unknown language.
While scholars still don't know the details they have been able to piece together some information of value. The Eastern Realms are presumably several larger islands closely connected, they are surrounded by dangerous waters filled with nightmarish creatures and the lands themselves seem to be cold and harsh.
So far several expeditions have been formed in an attempt to return to the realms however none have ever returned.