The Invaders are known to have entered the Playground in September 2001, a year before the Midgets. Very little is known about the Invaders before they came into contact with the Midgets, but according to their leader, Leo, they inhabited what would soon be known as the Midget Base. The Invaders were about eight to ten strong, led by a core membership of three or four girls, of whom Leo was in charge. On 9 September 2002, the Midgets entered the Playground, immediately occupying the Midget Base and naming it after themselves. The Invaders swiftly demanded that the Midgets leave the Midget Base, but refused to come to any compromise. Midget Master Daniel refused the Invaders' demands, upon which the Invaders attacked them. The Midget Army fought back, throwing sand from the ground at the Invaders to drive them off - this tactic was successfully repeated every subsequent time that the Invaders attacked.
Deprived of their former territory, the Invaders were forced into a nomadic existence, wandering the Lower Playground and Line - a few Invaders which attempted to settle in the Rebel Side were forced out during the Midget Civil War. At first, the Invaders attacked the Midget Base very frequently, sometimes every day. By the summer of 2003, these attacks had become less frequent, and by the start of 2004 were very sporadic. The Invaders disbanded around July 2004, prompting Midget Master Daniel to finally declare victory against them.