Given the current tensions between the Muslim and Judeo-Christian worlds, it's hard to imagine a musical program that can unite them.

But three ensembles visiting Ann Arbor tonight will do just that. Performing selections from the medieval masterwork "Cantigas de Santa Maria," the Boston Camerata, the Camerata Mediterranea and L'Orchestre Abdelkrim Raiz of Fez, Morocco, will offer a glimpse into Medieval Spanish music and a thoughtful king who brought three cultures together in song.

A profoundly religious work, the "Cantigas de Santa Maria" is a collection of more than 400 sacred songs dedicated to the Virgin Mary. The program originates from the Spanish King Alfonso X, who lived from 1221-1284 and was referred to as King Alfonso the Wise. While the program's composer is unknown, it is believed that Alfonso was the largest artistic influence, blending together Christian texts with instruments and sounds of the Muslim and Judaic world.

In researching the history of the "Cantigas," Boston Camerata and Camerata Mediterranea Musical Director Joel Cohen visited Morocco and Spain and looked at how the piece was originally performed. Tomorrow's performance features many of the same instruments present in medieval Spain, such as the rebec, an early form of the violin. Many of the percussion instruments used in the concert, such as the darbouka, taar and ud, are still played today in the Mediterranean basin.

In deciding which songs to perform at the concert, Cohen said he wanted to pick the ones that best reflected the original manuscript. "You can only give a sampling really," he said. "I wanted to use the ones that were very beautiful and fit the talents of my soloists."

Cohen is particularly interested in how the diversity of King Alfonso's court reflects contemporary American culture. Alfonso himself was half-German and always ensured that the composition of his court reflected Spain's many ethnicities. Initially, the events of Sept. 11 never factored in performances of "Cantigas," but due to the tragedy's lasting impact, Cohen can see the connection. "I certainly began it for the music, but look at this mess we're in," he said. "A bunch of Jews and Muslims and Christians on stage working together - sure that means something."

Tomorrow's performance marks the debut of all three ensembles under UMS auspices. The Boston Camerata, founded in 1954, is known for its unique programs, including several that focus on the music of particular religious groups or regions. In addition to numerous tours throughout Europe, Japan, Mexico and Canada, the group has undertaken ambitious projects such as "Simple Gifts," a historical chronicle of Shaker music in America. As the Camerata's musical director, Cohen hopes to explore the music of the Jews of Morocco and American religious minorities in the future.

The Camerata Mediterranea, founded in 1990 by Cohen, is the European-based sister ensemble to the Boston Camerata. They, along with the L'orchestra Abdelkrim Rais, one of Morocco's preeminent practitioners of Arabo-andalusian classical Spanish repertoire, perform with the Boston ensemble several times throughout the year.