Technically speaking, the beef between Pusha T and Drake is really a proxy war. In 2002, the duo Clipse (comprised of Pusha and his brother, then known as Malice) guest-starred on the track “What Happened To That Boy” by Birdman, the head of Cash Money Records and Drake’s boss.
The track was produced by Pharrell, who had discovered and signed Clipse to his own record label; according to Pusha, Birdman never paid Pharrell for his production work. So, out of a sense of loyalty to Pharrell – who is too easygoing to engage in this kind of dispute – Pusha adopted the beef as his own. (The Washington Post put together a nice timeline if you want to follow along.)