The main entry point for any north-eastern state is Assam, if one is entering from within India. There are a few entry points from Bangladesh Dawki in Meghalaya and Myanmar Moreh in Manipur but entry is restricted to local traders/govt. officials.
Note that entry into the states of Sikkim, Arunachal Pradesh, Nagaland, Manipur and Mizoram requires a Protected Area Permit PAP for non-Indians and an Inner Line Permit ILP for Indian citizens. Permits are issued by the Ministry of Home Affairs, but the easiest approach is to get your Indian visa with a special endorsement allowing travel in the state you wish to visit. Individual travelers are generally granted 15 days extendable once, but are allowed access only into major towns and sights; travels off the beaten track generally require a registered tour group of four or more people.
As of 1 Jan 2011, the Government of India has decided to exclude the states of Manipur, Mizoram and Nagaland from the Protected Area regime notified under the Foreigners Protected Areas Order 1958. This programme is being trialled for one year. However, it is advised that travellers still print out the relevant news articles from local news sources such as the Nagaland Post and Morung Express to show to border officials.Foreigners are still required to register with the FRO Foreign Registration Office of each district within 24 hours of arrival.
By train
There are good train connections from most of the major Indian cities to Assam. Incidentally, Assam is the only state in region with rail lines barring Nagaland with one station-Dimapur. The important station in Assam are Guwahati, Bongaigaon, Lumding, Tinsukia and Dibrugarh.The fastest train from Delhi is Guwahati bound Rajdhani Express 28 hrs followed by North-East Express 32 hrs and Dibrugarh bound Brahmaputra Mail 42 hrs, while the fastest train from KolkattaHowrah is Saraighat Express. Train track in Assam is not electrified and is single lane, so delays are a norm.There are narrow gauge trains to Arunachal Pradesh and Barak Valley area but they are very much prone to cancellation, delays and are not at all comfortable.
By plane
AssamGopinath Bordoloi Airport, Guwahati, Manipur Imphal Airport, Nagaland Dimapur Airport and Tripura Agartala Airport have direct flights from other parts of India Delhi and/or Kolkata. There are two other major airports serving upper regions of Assam and neighbouring areas - Dibrugarh Airport and Silchar Airport. There are helicopter services to Naharlagun 14 km from Itanagar, Arunachal Pradesh and Aizawl Mizoram.
By road
All the states have good network of roads in urban areas. There are regular long journey buses from West Bengal to many north-eastern states.Self-driving is not a good idea as all roads pass through heavy forest reserves and areas infested by insurgents.