Japanese motorcycle manufacturers began challenging the European factories for supremacy in the motocross world by the late 1960s. Suzuki claimed the first world championship for a Japanese factory when Joël Robert won the 1970 250 cc crown. The first stadium motocross event took place in 1972 at the Los Angeles Coliseum, and was promoted by Mike Goodwin and Terry Tiernan, then-president of the AMA. The event was won by 16-year-old Marty Tripes. This event paved the way for constructed, stadium-based motocross events known as Supercross. In 1975, a 125 cc world championship was introduced. European riders continued to dominate motocross throughout the 1970s but, by the 1980s, American riders had caught up and began winning international competitions.