Soul music was the result of the urbanization and commercialization of rhythm and blues in the '60s. Soul came to describe a number of R&B-based music styles. From the bouncy, catchy acts at Motown to the horn-driven, gritty soul of Stax/Volt, there was an immense amount of diversity within soul. During the first part of the '60s, soul music remained close to its R&B roots. However, musicians pushed the music in different directions; usually, different regions of America produced different kinds of soul. In urban centers like New York, Philadelphia, and Chicago, the music concentrated on vocal interplay and smooth productions. In Detroit, Motown concentrated on creating a pop-oriented sound that was informed equally by gospel, R&B, and rock & roll. In the South, the music became harder and tougher, relying on syncopated rhythms, raw vocals, and blaring horns. All of these styles formed soul, which ruled the black music charts throughout the '60s and also frequently crossed over into the pop charts. At the end of the '60s, soul began to splinter apart, as artists like James Brown and Sly Stone developed funk, and other artists developed slicker forms of soul. Although soul music evolved, it never went away -- not only did the music inform all of the R&B of the '70s, '80s, and '90s, there were always pockets of musicians around the world that kept performing traditional soul.