Bhangra began as a Punjabi folk tradition that celebrated the harvest, taking its name from the widely cultivated "bhang," or hemp. Bhangra eventually caught on in the city, and its lyrical themes inevitably turned from farming to love. As the music migrated, recent Asian immigrants took up with Bhangra in Britain and added synthesizers and guitar to its homespun sound, rocketing its energy upward while dismaying purists. It quickly caught on as the dance craze for expatriates from the Indian subcontinent, as it pulled in influences from hip-hop, Ragga and rock to replenish its storehouse of ideas. Raucous and joyous at its best and flashy and synthetic at its worst, Bhangra has never fully caught on in the mainstream outside of India and Pakistan, but its devout following has generated clubs in London exclusively devoted to the style. Driven by the deep sound of the dhol -- a barrel drum -- and later the double-sided dholak, the music is particularly festive and spirited, often featuring shouted, soaring vocals.