Tibetan drivers will now be checked for proper documents as China prepares for top-level Party meetings in faraway Beijing.
The event follows other religious gatherings held without interference by authorities in recent years.
'Consequences' are threatened for anyone caught viewing or sharing politically sensitive material ahead of an important Party Congress.
No one may enter Tibet during top-level Party meetings scheduled next month in Beijing.
The move restricts travel by the Tibetan minority group despite official guarantees against discrimination.
Chinese soldiers and civilian officials ask locals' help to extend road farther into Nepal.