||Sefer ha-Yashar is a medieval retelling of biblical stories arranged according to the weekly parshah, written in a contemporary (medieval) style. The text of the title page begins that it is a work including many stories and midrashim from the rabbis of blessed memory on the Torah, and the books of Joshua and Judges. It is written in a clear and pleasant style that draws a person’s heart to recognize the wonders of the Lord and His kindness. The text is in a single column in rabbinic type. Sefer ha-Yashar is not to be confused with the work of the same name attributed to Rabbenu Tam. The anonymous author of Sefer ha-Yashar is presumed to have liven in the 11th century in Spain. He retells, at great length, the story from the creation to the time of the Judges. It is the most complete example of this type of medieval writing using biblical motifs, aggadic material, and fictional innovations to weave a new and captivating story. The literary scope of the work was unequaled by any later medieval writing.
The author of Sefer ha-Yashar, together with the author of Jossipon, is credited with adding another aspect to the medieval story about biblical times: they attempted, and frequently succeeded, in incorporating non-Jewish legends, history, and mythology into the biblical story. The Jews of the Byzantine Empire, Italy, and Spain accepted the legends and history of the people among whom they lived as being part of the history of the world, and argued that as such they form part of the Bible which was believed to include all the important events in human history. These authors, and others, therefore, developed a system of synchronization and analogy to establish a connection between non-Jewish stories and biblical heroes and chronology.