When the gates appeared, Maximus or Max was the army chief, the one who had the power to control the whole army.
At the time the Raider Association was founded, Max decided to make his own force.
He had worked for the government his whole life, and he knew how they worked and what they did, but he didn't want that anymore, he wanted actually to do some good for the citizens.
When Max created his force, the main power of government which is the army was split into two groups, one who was loyal to the government, and another who was loyal to the army.
There was a long internal fight between them, and the fight is still going on as the government wants the power that Max has control over.
Max had too much power along with too much money, and that was something that was very dangerous for the government or the Association.