Over a hundred years ago, Thailand was forced to demarcate its borders with two imperial powers, Britain (which ruled Burma and Malaya) and France, which had colonised Indo-China, including Cambodia.
Some maps helping define the borders between Thailand and states under protection of those imperial countries were drawn up. However, these were not officially accepted by Bangkok, especially those covering the border between Thailand and Cambodia.
I den här länken kan man läsa mer om gränsdragningen
både på land och till havs