If you can not accept the fact that Tribals are not Hindus why you try to preach others what they should do at North East? Why don't you do that???
Who has given you the authority to demand from others what they should do?
Yes, there is a need to have a stronger law to punish all those who plays with tribals in the name of their religion be it Hindus or Christians. Why don't you write to the government about what the British have done. Not only the missionaries but the Vanvashi asrams which are also the den of playing the dirty game of converting tribals to Hinduism should also be asked to leave the area. The fundamentalist face in you is seen in your words.