[11] The concept of an official rabbi performing administrative duties and acting as an intermediary existed as far back as the 13th century in the kingdoms of Castile, Aragon, and Portugal and elsewhere in the Iberian peninsula.
[8] The term arrabi is attested from the late 12th century in Latin and Portuguese under Afonso III, and is mentioned in a judicial sense in municipal legislation documents.
Documents from Lisbon, Leiria and elsewhere suggest that there was one arrabi per community, who was an outpost of royal authority, parallel to and separate from the traditional rabbi who tended to their flock's religious and spiritual needs.
[9] The position of arrabi mor emerged in Portugal as a result of efforts begun in the 12th century to centralize the legal and fiscal system in the country.
Following the carnage and forced conversions in the 1391 massacre of Jews in Seville and its aftermath in other kingdoms of the Iberian peninsula, the devastation threatened to spill across the border into Portugal, but Moses Navarro exercised his power and influence with the monarch and his knowledge of edicts from the Vatican by Popes Boniface IX and Clement VI friendly to Jews to prevent any harm from coming to Portuguese Jewry.
[15] King John upon hearing of the edicts, immediately promulgated a law on July 17, 1392, prohibiting any persecution, which was obeyed gladly by his subjects due to the extent of his popularity in the land.