Yup. Although i must add not all muslim are illegal. Some of them are natives who settled here many centuries ago and now considered an important part of greater assamese society. Also that, religion is not important, native dislike illegals of all kind including hindus,buddhist and muslims from BD, animist ,buddhist,christians from Burma.
Nepalese citizens are only tolerated because they have treaty with India. Bhutanese citizens often come to India and use Indian highways to travel to their places and are only foreigners (from neighbouring nations) that are liked very well.
Tripura is not muslim majority but hindu Bengoli majority state. The original inhibitants, Tripuri people are ethnically related to Dimasa-boro-kachari tribe of assam and konyaks of nagaland and speak mutually intelligible dialect. The tribal king got aryanised very early and adopted hindu customs and later on mughal had some influence over the kingdom during their rule of plains of Bangladesh which allowed trickle of bengoli settlers in Tripura.This accelerated during the partition and now bengolis form the majority of the population. Famous bollywood musician like Sachin Devbarman and Rahul Devbarman are ethnic tripuris.
The state of Nagaland(except for border town of Dimapur), Mizoram and Arunachal require inner line permit(ILP) for both domestic and International visitors, which can be obtained very easily without much hassle. Meghalaya and Manipur can be visited without ILP although there have been some demands lately to introduce such system due to threat of illegal migration. Also in the state of Nagaland, Mizoram, Arunachal, Meghalaya and most of Manipur , non natives cannot buy land and settle, infact land is owned by the clans and individual ownership is not practiced legally,which offers some impediment for outsiders to settle here.
edit:
lol, I wrote too much sensitive stuff. Here enjoy this choir performance
Naga Folk fusion vocals performed by the Chakhesang Baptist Church Kohima.