No one would mistake a recent in-store performance at Amoeba Records in Hollywood for the time Paul McCartney played there last year. For that visit, the sprawling music retailer was jam-packed, every inch between the CD bins taken up by worshipful fans. This night business was moderate at best, shoppers casually browsing the vast expanses as Etran Finatawa took the stage. A couple dozen people gathered in front of the stage, apparently there specifically for this. But quickly others started to take notice, even before the music started -- understandably, as it was a visually colorful ensemble strolling out: five West Africans, two of them wearing long, blue-tinted robes and turbans, the other three in brown tunics and bright yellow stripes painted from the tops of their foreheads to the tips of their noses, each with a single feather sticking straight up from his head.

Then they started playing, one of the two robed men playing a Stratocaster, the other four providing percussion, all five singing and/or chanting. The guitar lines had a bluesy insinuation, the chanting too, together forming circular lines over the burbling rhythms. It was simple but mesmerizing. And surely throughout the store among those who had apparently not come to see the group, heads came up, shopping ceased and people were one-by-one drawn toward the stage. By the time the group finished its 40-minute set, most other activity in the store had come to a standstill and all eyes and ears were trained on the stage.

And that is the clearest demonstration you could have as to how and why the music of the Tuareg and Wodaabe nomads from the Saharan desert of Niger and Mali has become if not the then one of the true phenomena of global music at a startling speed. The Rough Guide to World Music's first edition published in 1994 had just one passing reference to the Tuareg. The third edition, published in 2006, contains a full chapter. The Mali-based Tuareg group Tinariwen, of course, is the star of that scene, its vibrant and forceful laments of and broadsides about the displacement, marginalization and economic/environmental issues threatening the desert people having been championed by Robert Plant, the Rolling Stones and many others.

With the door open, a steady stream of music from the nomads of that region has made its way to the rest of the world. Etran Finatawa, which is continuing its tour across the U.S. and then to Europe, is perhaps unique among them in its mix of the two tribes (the two robed men at Amoeba being Tuareg and the other three Wodaabe) and music involving both the bluesy guitar styles the former culture has adopted and the ceremonial chants of the latter. As in this performance, the music on the 2006 album 'Introducing' and the recent 'Desert Crossroads' is a seductive blend. (Listen to the track 'Kel Tamascheck' in the MP3 below.) It's a sound that has had the same effect shown on the Amoeba crowd on many others, including other musicians -- so many that the group's next album, members mentioned after this set, will likely be of collaborations, including with Malian guitarist Vieux Farka Toure, German eclecticists 17 Hippies and several acts from the U.S. and Mexico.

Even within the strictly Tuareg community a variety of approaches has emerged. 'Abacabok,' a 2006 album by the band Tartit (overseen by Belgian producer Vincent Kenis, the same force behind the Congotronics series) takes a largely traditional approach with songs telling of nomadic life and community. Toumast, which includes a cousin of one of the Etran musicians, takes a slightly more modern approach. And then there's 'Akh Issudar,' a gripping new album by Terakaft, featuring two former Tinariwen members who take up that group's freedom-fighter pointedness of Tinariwen (singer/guitarist Kedou ag Ossad was a key figure in the Tuareg Rebellion in the '90s) and sharpens it even further.

But the first appeal of all of this remains what was demonstrated at Amoeba.

"In general, people are interested in the sound," says Sandra Vanedig, Etran's German-born manager, who has lived in Africa for 11 years as a social anthropologist. "It's the blues and stuff, reminds them of being free and of freedom. It's very important, a romantic idea of living in the desert, the desert sound. People really like something that has to do with freedom and creativity, and this is a very important aspect of this music. You can feel the freedom, the rhythm of the camel walk that is behind the music."

Yes, but also walking behind the music has been an increased awareness of the cultures involved, and Etran, with its representation of two cultures, is in a strong position to boost that.

"Niger is really a victim of climate change, so that in the last decades it's been getting more and more difficult to live there with the old way of life," Vanedig says. "There were big droughts in the '70s and '80s, many people moved to cities."

Those experiences are part of what has brought the Tuareg and Wodaabe together in the group.

"They are nomadic cultures, they live in the Sahara, there are similarities," she explains. "But they speak two very different languages. The Tuareg originate in Morocco, the Wodaabe belong to a big family coming from East Africa, very different origins. The cow is very important for the Wodaabe. For the Tuareg it's the camel. Two languages that are different. Two musical styles that are different. The Wodaabe music is a polyphonic tradition, one main singer, then others behind him, not using instruments. Tuareg always use instruments, so bringing instrumentation to Wodaabe songs is very new."

However, she says, within Etran Finatawa it has become clear that despite the differences, "the philosophy is similar. The environment that was given them has influenced the way of living in very harsh climes, difficult environment. There are different mentalities, but the philosophy is not different."

For her and the musicians, and it seems for all the acts that have emerged from that area, it has become a mission to share the culture and to draw attention to the issues at hand amid the continued strife at home, though while walking some fine lines.

"Can't do everything," Vanedig says. "When you're onstage it's not the same as being in the grasslands. People have to be aware that this is a professional music group, not folkloric or something. This band is together four years, rehearsing and modernizing the music. They don't want to give the image of a dying culture. They want to show this is a living culture. This is a band wanting to make a fusion of this with other things. At first it was not easy, their own people did not want a fusion. But people back home are changing. This is modern but also enriching -- a new creation. So I wouldn't say we have the possibility to show everything, but we can get a little idea of this rich culture on stage. It's been important already."

Listen to 'Kel Tamascheck'