Hello Ganaa,
The payout methods available to you in Mongolia will be displayed when you try to add a payout method. If the one you want isn't shown on the page then it's not available.
To add a payout method log in and click on your profile photo. then select "Account settings". Then click on "Payout preferences" and you'll see the "Add Payout Method" button.
You could contact Airbnb support to discuss the issue.
Type "contact airbnb" in the "Search the community" box on these forum pages where you posted your question. Scroll down a little in the list of suggestions that appears and click on the "Contact Airbnb: A Community Help Guide[UPDATED]" one. That lists phone numbers and ways to contact them via Twitter or Facebook.
Steve.