In the first version of League of Legends, Chen Mo planned to have 25 Champions and five positions, with each position having five Champions. The difficulty was from low to high.
At the beginning of League of Legends, there was no top lane, mid lane, jungler, Archer, or support. At that time, there was still the Archer who played mid, and the lineup and tactics of passersby games were very chaotic.
However, in the S2 period, some of the top teams in Europe developed the "EU style," which was a double-player method for top, mid, jungler, and bottom lane. It was accepted by the fist and became the official designated lineup configuration of League of Legends.