State/Province display for a contact shows a number instead of the name for Vietnam contacts
Actually I don't think it is the ID, rather it is the 'abbreviation' which in the case of Viet Nam have all been entered in to table civicrm_state_province as numbers.

SELECT * from `civicrm_state_province`
WHERE country_id = 1233


whereas eg US ones are of type WV (West Virginia) etc

I don't know how bad it would be to suggest you copy the 'name' field and paste in to the 'abbreviation' field as a really bad hack.

I know I also raised this on the forum in the past with the hope of a solution so that there was a setting you could nominate to use either the Abbreviation or the Name on the Contacts Summary screen