We're three pages in, guess the actual convo's gotta start somewhere... '73 was not the beginning of RECORDED hip-hop music, it's documented as the beginning of where the culture of it began taking shape. There were no actual records until '79, but it was growing before that with MCs on the mic at the parties where the DJs and dancers were already the stars of the show. These parties grew in popularity, and the MCing grew with it. First there were solo MCs, then MC groups, it gradually became a popular part of the parties. Then, it translated to them actually making records, especially after "Rapper's Delight" became a hit (ironically done by a put-together group of dudes who weren't previously known on the scene). Once that took off, that's when MCs started putting out records, which of course started hip-hop growing into a genre over the years.