The clans, though barbaric, were not foolish. They knew that such a move might lead to internal strife before they could master the power. Then, when the Empire people quietly manipulated things and supported a second-in-command to incite further in-fighting, the clan leaders would eventually fall under their control. So, the strongest seven clans at the time gathered together and devised a plan both crude and brilliant.
They gathered the most trustworthy elites from the seven clans and came up with a resounding name, "Ustus", claiming it to be the strongest clan in the northern continent. As it was the first time both parties negotiated, coupled with the language barrier, the Empire people saw the clan members as all spirited and mighty, and truly didn't see through this little trick, thus believing it.