Are the terms ‘border’ and ‘border line’ synonymous? Is the linear model the only possible means by which to define a boundary? Is there any other method, other than the demarcation of a single boundary line, of depicting the confines of suzerainty and territorial lordship? Is it plausible that a political entity, even a medieval one, could exist without defined border lines? As I have maintained in chapter 8, many of the scholars who dealt with the history of the Frankish kingdom assumed as a matter of fact that the Latin Kingdom of Jerusalem had external political boundaries, that the terms border and border line were synonymous, that borders were usually natural borders, and that there was a connection between border lines and castles.

Controversy arose primarily concerning how borders were defended and the role of castles. Were castles located along the borders in order to defend them, or were the linear borders demarcated on the basis of the castles' locations? Only very few scholars agreed with Raymond Smail, who rejected in toto the assumption that castles were erected to prevent the incursion of enemies into the kingdom from across its external border lines. Other scholars (especially Deschamps, but also Pringle, to a lesser degree) assigned greater importance to the assumed connection between highways and roads and castle locations. However, it would seem that none of them rejected the basic assumption that a political border did indeed separate the Crusader kingdom from its neighbours.