When he uploaded his 2015 debut single, “White Iverson,” to SoundCloud, the rap crooner known as Post Malone was an unknown 19-year-old with a platinum grill and a prayer. Upon the release of his second mixtape a year later, the Texas native was one of the buzziest and fastest-rising rappers in America. That mixtape, August 26, was his first for Republic Records—and to be clear, it dropped on May 12, 2016. Its title was intended to alert fans to the release date of his forthcoming debut album, Stoney, which in fact would not come out until December 2016. But that’s neither here nor there. August 26 was the first full-length introduction to the record-setting, genre-spanning musician who would go on to write chart-topping hits in his sleep—though as Post made clear on the 2 Chainz-featuring “Money Made Me Do It,” “I had a mil before the label.” (In the words of 2 Chainz: truuu.) The tape is also a time capsule for the period of the 2010s when radio-friendly trap music cross-pollinated with the new, experimental SoundCloud scene. August 26 offered stripped-down sex jams like “Git Wit U” and the Jeremih duet “F**k” on one hand, spacey collabs with up-and-comers like Lil Yachty and iLoveMakonnen on the other. But perhaps the clearest vision of Post’s future could be found in the curveballs, from “Hollywood Dreams / Come Down”—a cover of Fleetwood Mac’s “Dreams” that gave way into a ballad for the afterparty doldrums—to “Oh God,” whose twangy vocals might have been a premonition of his 2020s country turn.