In the contemporary era of AAU basketball, it's not uncommon for players to have had long relationships with one another, going back years before they turn pro.
Such ties, however, are usually shared by players within a few years of each other, and form when the raw, future NBA players end up playing each other, or attending the same camps. It's far less common for players separated by a half-decade to have had such an opportunity, but Jayson Tatum's preternatural talent ended up piquing the attention of Anthony Davis.