Border conflict has roots in colonial maps and long-standing ‘sibling rivalry’
Thailand and Cambodia have been locked in a border dispute for more than a century, which exploded again in the summer of 2025. Peace efforts have had mixed results and fighting continues.
A historical dispute over lines drawn on colonial maps is often used as a pretext for simmering nationalism. The two countries have had what one historian called a “sibling rivalry” for decades, fanned by competing claims to the region’s rich cultural heritage, including ancient temples in disputed areas.
Competing territorial claims date back more than a century, when France occupied Cambodia, which was part of French Indochina.
Compared with today, the border between Thailand – then known as Siam – and Cambodia – then part of French Indochina – lay further to the south. As a result, Cambodia was smaller than it is now.
