Koopas were subject to severe racism back when the Mario Bros were babies. Morthophelus Koopa I, then king of the Koopas' homeland, was a nice leader and treated the Koopas well. However, he went insane and declared war on the Toads when they segregated themselves from the Koopas and King Louis Toadstool II stated that he didnt want "those damn turtles [slur against Koopas] anywhere near [their] kingdom". The Koopa Uprising caused several lives to be lost. The king could not go on, knowing that he indirectly killed thousands of his men. He then decided to end his life by standing on a bridge and cutting it down with an ax. The late King Koopa's son, Prince Bowser Koopa, was told that his father was assassinated by a Toad. When he grew up, he set in motion the plot of Super Mario Bros, as stated in the manual.