The concept of a continuous boundary line is a modern cartographic invention

Evidence

Boundary-stones and similar markers did exist, and indeed multiplied along the western fringes of the realm as the British pressed in from Lower Burma. But these stones were set up discontinuously at strategic mountain passes and fords, and were often substantial distances from corresponding stones set up by the adversary. They were understood horizontally, at eye level, as extension points of royal power; not ‘from the air.’ Only in the 1870s did Thai leaders begin thinking of boundaries as segments of a continuous map-line corresponding to nothing visible on the ground, but demarcating an exclusive sovereignty wedged between other sovereignties. — Benedict Anderson, Imagined Communities, 659

Categorization

• XREF: Builds on the ear/eye bias distinction from Communication as Culture — different sensory-tech regimes produce different conceptions of territory.
• SHARE: A geographer or map historian friend would savor the pre-cartographic Thai understanding of boundaries as discontinuous eye-level point-extensions of power.