It is definitely not optimal, but possibly by design: priority is tiles that are easily accessible by your peoples, and people travel faster using roads, following rivers, going through plains ... than through hills, forests or jungles. So it makes sense for those tiles to naturally be added to your empire quicker. (I think you only pay road maintenance for roads inside your borders, which makes border growing on road actually detrimental, but I might be wrong on that) EDIT: you can play with the coefficients in CBO/Balance Changes/CoreDefines.sql. They have name like PLOT_INFLUENCE_RESOURCE_COST. (Note that bonus ressource only get half of the bonuses for "being a resource", but still get normal points for having more yields than basic tiles). The core of the problem is that the function doesn't take in account all the bonus yields from pantheons and buildings, since tiles outside of your border do not get any bonuses, which means the game does not see that those bonuses resources will end up be worth much more than what they seems. It doesn't look easily fixable from the code structure, unfortunately.