With the rise of disco in the US and punk rock in the UK, hard rock's mainstream dominance was rivalled toward the later part of the decade. Disco appealed to a more diverse group of people and punk seemed to take over the rebellious role that hard rock once held. Early punk bands like The Ramones explicitly rebelled against the drum solos and extended guitar solos that characterised stadium rock, with almost all of their songs clocking in around two minutes with no guitar solos. However, new rock acts continued to emerge and record sales remained high into the 1980s. 1977 saw the début and rise to stardom of Foreigner, who went on to release several platinum albums through to the mid-1980s. Midwestern groups like Kansas, REO Speedwagon and Styx helped further cement heavy rock in the Midwest as a form of stadium rock. In 1978, Van Halen emerged from the Los Angeles music scene with a sound based around the skills of lead guitarist Eddie Van Halen. He popularised a guitar-playing technique of two-handed hammer-ons and pull-offs called tapping, showcased on the song "Eruption" from the album Van Halen, which was highly influential in re-establishing hard rock as a popular genre after the punk and disco explosion, while also redefining and elevating the role of electric guitar.
What two genres made inroads on hard rock in the 1970s? (If the question is unanswerable, say "unanswerable")
disco in the US and punk rock in the UK