Why was the hittites reign short

Once Hrozny’s work was published, however, it initially both clarified and obscured the history of the Hittites. There had long been an accepted theory among scholars of ancient history that India was invaded from the north by Indo-Europeans known as Aryans (the so-called `Aryan Invasion’) and that, somewhere, there existed a homeland from which these invaders descended into India. The texts uncovered by Winckler seemed to corroborate this theory. Since there was no evidence that Indo-European languages were known in Anatolia at that time, it was postulated that there had to have been some kind of invasion and, most probably, from the same mysterious homeland from which the alleged invasion of India was launched.

so whats the answer? ?