There are natural barriers that prevent competent but distant nations from conquering dysfunctional ones. Colonialism was an attempt to ignore those, until people realized that it cost far more than it was worth to the colonizers.
I should probably mention that much of the reasoning behind the Bush invasion of Iraq was along these lines. It was hoped that Iraq would become a "beacon of democracy" in the Mideast. Then, all of its neighbors would either adopt Western institutions to maintain their relative positions, or they would be conquered by a U.S-supported Iraq.
Somebody forgot to factor in the effect of an 8000-mile supply line, or the reluctance of a people to give up deeply-entrenched customs.