Prey Veng Province
The modern-day postmark, below, for Prey Veng provincial centre in South-Eastern Cambodia:

The Prey Veng postmark from 1908, below, under French colonial rule:

Related Sites:
Tourism of Cambodia Travel Guide to Prey Veng: http://www.tourismcambodia.org/provincial_guide/index.php?view=detail&prv=19
and also: http://www.tourismcambodia.com/travelguides/provinces/prey-veng/