Although he was Catholic, King Alfonso X of Spain (1221-’84) demanded tolerance of Islam and Judaism–earning him the epithet “King of the Three Religions”–and he went so far as to encourage artistic and musical cross-pollination. One fruit of this cultural exchange was the Cantigas de Santa Maria, a collection of more than 400 sacred songs in praise of the Virgin Mary; some were composed by, and all were approved by, the monarch himself. Though they deal with Christian themes, the songs fuse elements from a range of Mediterranean traditions. For the past few years musicologist and lutenist Joel Cohen, who heads the esteemed early-music ensemble Boston Camerata, has pored over the manuscripts to see how the songs could be most authentically revived. While notations for the melodies and rhythms have survived, the texts do not indicate what instruments should be played. So Cohen turned to Moroccan practitioners of classical Arab music and discovered a tradition, passed orally through the generations, free of the “oriental” microtones typically associated with non-Western music. Instead, it has much in common modally with Gregorian chant–which means that the Cantigas could easily be adapted to this style and played on oud or Moroccan violin. Cohen organized a collaborative project between the Boston Camerata, Camerata Mediterranea (a sister ensemble he started in 1990 to specialize in the early music of the Mediterranean basin), and the Andalusian Orchestra of Fez to record some of the Cantigas (released on Erato). Members of the first two groups, violinist Mohammed Briouel of the Andalusian Orchestra of Fez, and the ad hoc Sharq Arab-American Ensemble (in lieu of the orchestra, whose members were denied visas) are on a U.S. tour performing a selection from the Cantigas, sung in medieval Spanish. The notion of world music is older than we thought. Tuesday, November 5, 8 PM, Mandel Hall, University of Chicago, 1131 E. 57th; 773-702-8068.