Earlier struggles were local. Now the struggle area has become regional. At the outset the peoples were amateurs in the science and art of expansion, occupation, consolidation, exploitation. Through the hard school of struggle they became professionals. From victory to victory they gained in territory, in wealth, in administrative skill. One by one, rivals were eliminated, annexed or associated with the nascent empire which was by way of becoming the central empire of a maturing civilization. Generations of effort and centuries of time have gone into the empire building process. The farther the civilization has expanded, the greater the necessary input of manpower, wealth, enterprise and administrative talent needed to keep the enterprise strong, solvent, masterful. Eventually the expanding civilization reaches a point at which the costs of further expansion are greater than the income derived from further extension of its authority. Up to this point expansion had paid its own way. Beyond this point it is a losing proposition--politically, economically, sociologically. At this point begin times of troubles; bad harvests; colonial or provincial revolts; power struggles between individuals or classes in the homeland; new rivals moving in to share in the prospective plunder of the mother-city. From this time of troubles the civilization enters a new phase of its lifecycle. Up to this point victory has brought plunder and prosperity which have financed new foreign adventures and led to new victories. Beyond this point lies stalemate, economic stagnation, military defeat. Building an empire and establishing it as the central force in a civilization is a long and arduous process. Once the process is reversed, the decline may move quickly or slowly, but as it proceeds the civilization is fragmented and eventually dissolved or taken over by a more vigorous rival. At all stages of this cycle there have been life and death survival struggles. Peoples, nations and empires entered the contest, played their parts, made their contribution to the up-building process. There were ups and downs, advances and withdrawals, victories and defeats. There were many contenders for survival and supremacy. Usually there was one survivor which gave its name to the civilization. The period of ascendancy of any civilization has been historically brief. The struggle to the summit was long and exhausting; the descent from the summit more rapid than the ascent. Literally, like the bear that went over the mountain to see what he could find, and who found the other side of the mountain, the civilizations that have reached the summit of wealth and power have found on the other side of the summit a steep downward sloping time of troubles that ended in dissolution and liquidation.