The NBA started in 1946 or 1949, depending on how you count it (a merger between the BAA and NBL in 1949 resulted in the National Basketball Association but the league sees itself as the descendant of the BAA and the NBL teams were seen as expansion teams. Just in case you were wondering).
By 1956 Bill Russell had arrived to revolutionize the game and in 1959, Wilt Chamberlain joined him. The rivalry they had defined the league until 1980, when the Larry Bird-Magic Johnson rivalry took control.
Both men claimed, correctly, that Chamberlain was the greatest talent ever to play center.