The majority of tourists enter Mongolia through three entry points. By flight to the capital Ulaanbaatar (Ulan Bator). By train or car from China (Zamin-Uud border crossing). By train or car from Russia (Sukhbaatar/Altanbulag).
See the detailed Google map of all the border crossings, with data on each crossing. Zoom in and click the icons to see details.
Following is a description of - flight, train, road and trade border crossings.
All International flights land at Chinggis Khaan airport in Ulaanbaatar, with one exception - flights from Kazakhstan land in Olgii in west Mongolia, tourists are permitted to enter Mongolia through Olgii, with this flight.
A flight from Hailar in China does have a stop over in Choibalsan in east Mongolia, before reaching Ulaanbaatar, but tourists are not permitted to get off at Choibalsan.
For more see the Flights page - all airlines and all flight options into Mongolia.
For more see the TransMongolian train page for detailed train options.
The Zamyn-Uud/Erlian from China and Altanbulag/Kyakhta from Russia, have full services for tourists. The other three have limited services. The main issue is limited options for transportation across and beyond the border crossing. You may use one of the other three, in case you enter with your own car, bike, or pre-arrange for someone to meet you and take you across and beyond the border crossing. Crossing by foot is strictly prohibited. Bulgan border crossing is the latest (2011) to open up for tourists.
All road border crossings are closed on national holidays.
(Train and flights operate all year round).
Dates of closed borders: New year January 1st, three days of the Chinese lunar new year (annually occurs on different days of the month. in 2012 in January 22-24). May 01-03, October 01-03, tow days of the Mongolian lunar new year (annually occurs on different days of the month. in 2012 February 22-23). March 08, June 01, July 11-12, and November 26 annually.
For more see the road system page and public transportation for options.
Tourists can not enter through any of these crossings. They are used for trade mines export, and for locals with Chinese or Russian passports.
In addition to these there are several temporary border crossings used by local herders. For complete details see the Google map.