Isengard is a warlike faction, the brainchild to Saruman the White. Finding lack on intelect in Goblins and Mordor Orcs, Saruman created the perfect Uruk-Hai. Bred from Dunlendings and Mordor Orcs, the Uruk Hai are strong and only obey Saruman.
There is no much history to Isengard. It was established somewhere between S.A. 3420 and S.A. 3430 originally as a fortress with a wall called the Ring of Isengard and the tower of Orthanc. It was made to hold one of the seven seeing-stones, or palantiri. After the massive Dunland invasion of Rohan, Isengard was populated largely by the Wild-Men. After Saruman came from his travels from the East in T.A. 2759, he was gladly given the Keys of Isengard and settled in Orthanc.
In T.A. 2851, the White Council met and Saruman overruled Gandalf when he urged an attack on Dol Guldur. It soon became clear that Saruman desired to possess the One Ring himself. In T.A. 2953, following the last meeting of the White Council, Saruman took Isengard for his own and fortified it. As Lord of Isengard, Saruman began to bring trouble to Rohan by aiding its enemies.