History of Israel
Among theologians and biblical scholars, he is best known for his book, "Prolegomena zur Geschichte Israels" ("Prolegomena to the History of Israel"). After a detailed synthesis of existing views on the origins of the first five books of the Old Testament, Wellhausen's contribution was to place the development of these books into a historical and social context. The resulting argument, called the documentary hypothesis, became the dominant model for many biblical scholars and remained so for most of the 20th century. In the realm of Arabic studies, Wellhausen's greatest achievement remains "The Arab Kingdom And Its Fall".