Early humans were nomads. They moved from place to place in search of food and sometimes because of disequilibriums in their spaces. Their nomadic life-style established non-permanence of territory and dwellings. Therefore, they had no real desire to claim ownership of space. All that changed when humans became smarter and were able to figure out that they did not have to wander about in search of food: eureka agriculture. The discovery of agriculture caused humans to establish permanent farmlands and dwellings on fertile soils close to sources of water. The establishment of permanent settlements established the claim of ownership of space. It is important to note that space ownership is fundamentally a claim because no human or group of humans owns apriori Space. We all met Space already made. Even a man-made island exists in apriori Space. In order words, Space was apriorily given to all earthly beings for their collective use. This is evident in the free flow of movement of animals and humans during the Paleolithic Era which culminated in the Great Migration from Africa to the other continents. Birds still enjoy this freedom of inter-spatial movements.
The claim of ownership of space is justified if the claimant is the founder (discoverer) of the space and has worked hard to establish settlements in the space. When the claim of ownership of space is justified in this manner, it equates to the right to ownership of space which can be voluntarily or involuntarily transferred. Sale or inheritance of the right to ownership of space is an example of voluntary transfer of ownership. Conquest of space is an example of involuntary transfer of the right to ownership of space. This equality between justified claim of ownership of space and the right to ownership of space is the rationale for a nation's right to ownership of space.
What happens if the natural right to migrate in Space conflicts with a nation's right to ownership of space? Consider entity X in space s1 who decides to migrate to space s2. s2 informs X that X's migration into its space is subject to the immigration protocols of s2. A conflict of rights occurs, if s2 prevents X from actualizing its migration rights. In essence, X's natural right to migrate overides s2's right to ownership of s2. Only the right to secure space can overide the right to migrate into space. If X is proven to be a threat to the well-being of s2, then X can be prevented from entering s2 because X's natural right to migrate into s2 does not overide the natural rights of the inhabitants of s2. The inhabitants have the natural right to be secure in their spaces. In other words, all spaces have the right to secure their spaces.
In the context of immigration, the right to secure space overides the natural right to migrate into space. This security is often broadly defined. However, when it is used to overide an entity's natural right to migrate into space, it should be specifically defined and proved. Political and social fears of being politically or socially overwhelmed by immigrants is not a security issue for which immigrants should be blamed. These fears are understandable in a democratic political system of one person, one vote. Founders of space and their descendants detest the involuntary loss of the power of ownership of the space they founded. But immigrants are not to be blamed for loop holes in political and social systems established by founders of space or their descendants. The blame goes to those who allowed the loop holes to exist. The founders of most of the prosperous spaces in the western hemisphere never anticipated global browning. They never quite understood that democracy is a number game not a color game and that if you want to win the game always, you must have the numbers always. In a democracy, the initial founders' ownership of space becomes citizens' ownership of space. White citizens, black citizens and citizens of all colors in between, become collective owners of space with the equal share of one person, one vote.
Most mass migrations in modern times are results of man-made space disequilibriums (wars, bad and corrupt leaders, etc). So, the long-term solutions are simple. Stop wars and elect good leaders. In the short-term, the desire for security should be tempered with benevolence. Home is the most desirable place for most people. It is the need to survive that is the primary reason for mass migration.