The great empires that flourished between 300 BC and 200 BC can all be divided into the four factors that contributed to their rise. Although each empire faced prolonged periods of conflict, all four empires succeeded in imposing unity and order among the people. The rise of these empires can be attributed to four specific factors crucial to their construction. Factors crucial to the rise of great empires included a form of centralized leadership with enforced uniform legal codes, powerful military forces, a strong economy, and technological advances. Ultimately an efficiently run centralized government along with powerful military forces caused the success of empires, however in the same form non-decentralized leadership and military weakening attributed to the possible collapse of the great empire. Each empire was unified under a different government and often previously antagonistic peoples and states. However, no major ancient empires were governed democratically, but rather they were all hereditary dynasties. Hellenistic states, Rome under the emperors, and Han China recruited at least some officials on the basis of merit rather than birth. Relying on their schools to fill administrative positions, successful ones would in turn give efficiency ratings and on-the-job training, basing promotions on performance. In the Han example, administrators were chosen from a variety of formally educated men through an extensive selection process. However in Hellenistic states, literacy in Greek was essential for successful advancement in both the private and public sectors of society. To further ensure the success of empire governance, empires had enforced uniform legal codes. The Roman Empire... in the center of the card... announcements, ports, waterways, irrigation projects, defensive walls or other installations. The energies of the empire expanded to maintain security and improve the economies of those empires. The Great Wall of China, Roman roads and aqueducts, the enormous granary complex of the Incas, and the Ptolemaic irrigation works along the Nile River are prime examples of the expanded energies. to maintain security and improve the economies of those empires. Often built by force, all great empires built elaborate public works. Roman roads accelerated troop movements, internal trade, and international trade. The unfair economic burdens of trafficking and their direct impact on the empire's military forces. The poor economy has made technological advances due to the expense of starting and maintaining such large projects, often impoverishing the governments that supported them.