einfaldrar

Could you clarify what "einfaldrar" refers to? Is it a term from a specific language (Swedish, Icelandic, etc.) and a particular field (history, biology, linguistics, etc.)? Do you want the article in Swedish or English, and are there any specific regions or examples you’d like included? If you don’t have a context, I can provide a general, neutral encyclopedia-style overview of the concept of invasions or incursions.