Íslendingabók (Icelandic pronunciation: [ˈistlɛntɪŋkaˌpouk], Book of Icelanders; Latin: Libellus Islandorum) is a historical work dealing with early Icelandic history. The author was an Icelandic priest, Ari Þorgilsson, working in the early 12th century. The work originally existed in two different versions but only the younger one has survived. The older contained information on Norwegian kings, made use of by later writers of kings' sagas.
The priest Jón Erlendsson in Villingaholt (died 1672) in the service of bishop Brynjólfur Sveinsson made two copies of Íslendingabók (now AM 113 a fol and AM 113 b fol at the Árni Magnússon Institute for Icelandic Studies), the latter one because the bishop was unhappy with the first version. The original copied from is assumed to have dated to ca. 1200. It was lost in the course of the late 17th century, and when Árni Magnússon looked for it, it had disappeared without a trace.
Íslendingabók is a concise work which relates the major events of Icelandic history in terse prose. While the author is forced to rely almost exclusively on oral history he takes pains to establish the reliability of his sources and mentions several of them by name. He avoids supernatural material and Christian bias. The prologue of the book explicitly states that whatever might be wrong in the account must be corrected to "that which can be proven to be most true". Due to these qualities of the work and the early time of its writing, historians consider it the most reliable extant source on early Icelandic history.
Apart from a prologue and a genealogy at the end, Íslendingabók is split into ten short chapters.
Iceland is settled in the days of Harald I of Norway by immigrants from Norway. The first settler, Ingólfur Arnarson, arrives in Reykjavík. Previous inhabitants, a few Irish monks, known as the Papar, leave since they don't want to live with pagan Norsemen. When the first settlers arrive Iceland is forested "from the coast to the mountains".