Check out the video below for a quick introduction to rugby league:
In 1895 representatives of the 22 clubs based in the North of England decided to split from the Rugby Football Union (RFU) and start a new organisation called the Northern Union, which would become the Rugby Football League (RFL). The reason for this split was the desire to pay players for turning out for the clubs. At the time players worked 6 days a week and would have to take time off from work to play, which of course meant that they missed out on their work payment. This wasn't such an issue for clubs in the south of England where players were often wealthy gentlemen. However in poorer regions this was a problem. The Northern clubs had proposed to reimburse people for lost earnings but this had been refused by the RFU. They had seen how Football had recently become professional, and were concerned at the increasing numbers of working class people playing that game, a situation that they didn't want repeated with rugby!
Over the following years the RFL took steps to make the game more open and exciting for fans, in order to afford paying their players. They reduced the number of players to 13, removed the line out, reduced the number of points for a penalty kicks to encourage more tries and eventually introduced the play the ball after a tackle, giving us the game we know and recognise today as a distinct sport from rugby union.