Kronos Quartet and its artistic director/founding violinist David Harrington have long been known as interpreters of music from around the world, expanding the string quartet repertoire with works from across genres. Nonesuch, the Quartet’s longtime label, celebrates this remarkable curiosity in the group’s 40th anniversary year with two releases: the Kronos Explorer Series five-CD box set and a new album, A Thousand Thoughts, both of which will be available on April 8, 2014 (international release to follow on April 21). Pre-orders for both are available in the Nonesuch Store; pre-orders of A Thousand Thoughts include an instant download of Alter Yechiel Karniol’s Sim Shalom from the album, which you can hear below. Kronos continues its anniversary celebration with UCLA concerts on March 14 and 15, and a Carnegie Hall concert on March 28; for additional tour details and tickets, visit nonesuch.com/on-tour.

Kronos Explorer Series comprises five classic albums from five different parts of the world—Pieces of Africa, Night Prayers, Caravan, Nuevo, and Floodplain—with new liner notes that include an in-depth interview of Harrington by renowned author Jonathan Cott. Pieces of Africa (1992), Kronos’s first record of African music, developed over eight years, during which Kronos commissioned/performed with some of the continent’s greatest musicians, including Zimbabwe’s Dumisani Maraire, Nubian Hamza el Din, and Gambia’s Foday Musa Suso. Works with roots in Ghana, Morocco, South Africa, and Uganda also are included. Night Prayers (1994) contains seven works by vastly different artists, geographically all from within the former Soviet Union, including Huun-Huur-Tu from Tuva, Armenian duduk master Djivan Gasparian, and Sofia Gubaidulina from the former Tatar republic. The compositions on Caravan (2000) come from many compass points—Iraq, California, South America—but all have roots in other places, starting with the territory that links northeastern Europe with the Mediterranean and the Orient; composer Osvaldo Golijov arranged the pieces. For Nuevo (2002), the Quartet embraced Mexican genres from rock to mariachi, with music from the heart of regional Mexico, including street performers, religious festival celebrants, and a duet with a leaf player. And on Floodplain (2009), ancient songs from the wellspring of the Fertile Crescent mingle with new music from low-lying areas in Central Asia, North Africa, and Eastern Europe, performed on centuries-old harps, electric sitar, and instruments built for Kronos.

A Thousand Thoughts is a look at Kronos’ geographically wide-ranging sources. It features music from 14 different countries, including China, India, Sweden, and Vietnam. The album includes the four cellists who have been in Kronos Quartet over the last 36 years: Joan Jeanrenaud (1978–1999), Jennifer Culp (1999–2005), Jeffrey Zeigler (2005–2013), and Sunny Yang (2013–present). Ten of the album’s 15 pieces are previously unreleased.

For 40 years, the Kronos Quartet—David Harrington, John Sherba (violins), Hank Dutt (viola), and Sunny Yang (cello)—has pursued a singular artistic vision, combining a spirit of exploration with a commitment to continually re-imagining the string quartet experience. In the process, Kronos has become one of the most celebrated and influential groups of our time, performing thousands of concerts worldwide, releasing more than 50 recordings, collaborating with many of the world’s most accomplished composers and performers, and commissioning more than 800 works and arrangements for string quartet. In 2011, Kronos became the only recipients of both the Polar Music Prize and the Avery Fisher Prize, two of the most prestigious awards given to musicians. The group’s numerous awards also include a Grammy for Best Chamber Music Performance (2004) and Musicians of the Year (2003) from Musical America.