Civilizations have relied on many forms of government, each with their own strengths and weaknesses. The earliest rulers were acting on a combination of fear, cunning, and connections; however, with accumulation of wealth and economic power, they tended to rely primarily on instruments of oppression and intimidation. In response, the Greeks of Athens developed the first Republic with limited representation for its citizens. Still, the Republic's openness left it vulnerable to more militaristic, oppressive governments. This tension between freedom and security remained central to governmental development deep into the 3rd millenium.