In the '90s, hip-hop moved out of the streets into the world of big business. An avant-garde street art that expressed black consciousness lost its DIY ethic and became a commercially driven industry, spearheaded by Suge Knight and Puff Daddy.

A new underground has now emerged. Inspired by self-defence groups like the Black Panthers, Brooklyn duo Dead Prez represent a resurgent nationalist struggle, with politically hungry fans tracing M1 and partner Stic's aims to uplift and mobilize America's black community back to the sixties movement led by Huey P. Newton, Fred Hampton and Malcolm X, the same movement championed by Public Enemy in the '80s. Black music has always been its most exciting when at its most rebellious, so it's no surprise to find the Dead Prez debut Let's Get Free touted as the most important and revolutionary hip-hop record in over a decade.

The opus opens with Chairman Omali Yeshitela urging the black African population to rise against its white capitalist oppressors on the plaintive 'Wolves'; the penultimate 'Propoganda', an uplifting Fugees-styled classic, questions the mysterious deaths of many controversial figures.

In between, Let's Get Free remains a defiantly accessible, as it is lyrically confrontational. Dead Prez, at once, attack and use the mainstream: the massive single 'Hip Hop', the rock-infused sing-a-long 'Psychology' and the celebratory 'It's Bigger Than Hip-Hop' are the sort of infectious tracks that could and should be challenging the big boys and girls for MTV airtime.

From another end of the spectrum, Japanese turntablist and producer DJ Krush's brand of largely instrumental hip-hop has been predominantly politic-free. His three Mo'Wax albums Strictly Turntablized, Meiso and MiLight brought light to the otherwise dark tunnel that was '90s hip-hop. With his innovative mix album Code 4109, Krush expertly re-invents cuts from the likes of Beats International, John Klemmer and like-minded French pioneer DJ Cam, with the end result more remix than mix album.

Both collections remind us that hip-hop is an infinitely expressive form. In particular, the challenging raps of Dead Prez are a timely reaction against a generation of big-mouth, big-wallet egomaniacs.

The re-liberation of hip-hop has well and truly begun.