Popular music of the United Kingdom in the 1970s built upon the new forms of music developed from blues rock towards the end of the 1960s, including folk rock and psychedelic rock. Several important and influential subgenres were created in Britain in this period, by pursuing the limitations of rock music, including British folk rock and glam rock, a process that reached its apogee in the development of progressive rock and one of the most enduring subgenres in heavy metal music. Britain also began to be increasingly influenced by third world music (roots of World music), including Jamaican and Indian music, resulting in new music scenes and subgenres. In the middle years of the decade the influence of the pub rock and American punk rock movements led to the British intensification of punk