Who are the "Hill" people?

In the current movement of the Terai people, it's important to note who the Hill peoples are since the Terai separatist movement has created a difference between the "Hill" and "Terai" population. It is easy to forget thatthe real "Hill" people are the indegenous people. The so called "Hill" people are actually the descendents of the "Terai" people from the Muslim invasion of the 10th century. Those people in power-mostly the upper echelon in Hindu caste system-are not "Hill" people at all. Now, if we only consider Nepal's history from the time of unification, then the present conflect makes sense, but history did not start with the unification. Therefore, it is better to seek reconciliation and power-sharing through a federal system than what the movement is aiming for, a separate nation of 20 Terai districts.