The constant cycle of exploration, discovery and occupation is the fundamental means societies use to accommodate their growing numbers. Countries and groups of people through some advantage, often military force, and proceed to exploit it for commercial gain. When opposition impedes their progress the results can be dire. Genghis Khan, for example, was a power hungry opportunist that exploited his military abilities to claim lands and riches for himself. His was a series of ruthless campaigns, some of these pitting his forces against the Roman Empire when their rule was starting to fade. This clash of the titans demonstrates how even a renowned power can be assailed by a skilled tactician.
More to the point is how a vastly out-gunned population will invariably be stripped of their property rights or be coerced to trade them away. The American Indians are an excellent example of this. The discovery of America was for the sole intent of finding a shorter trade route to the east. It became a commercial venture which lead to immigration and settlers staking claim to land that, at the time, was not otherwise considered to be owned. The common belief being there was land enough for every one. Then cities grew and people spread out, causing the Native Americans squeezed in or pushed out. The Cherokees had found a way to fit in and still be their own nation. But when gold was discovered on their lands, the push to move the Indian populations that was already in motion gained new momentum and out they went.
Martians are likely not to exist. But if they do they may find themselves on the wrong end of the deal when we come to call. What is likely to happen when man lands on Mars? Most likely the landing party will plant a flag and claim it in the name of Virgin Atlantic (mabye they would go under the name of Virgin Galactic) or who ever paid for the trip. Then there is Martin the Martian to deal with. Would we end up the conquered people if they retaliated to our invasion?
