Why is the world divided territorially?

Is it me or isn't everybody gives importance to own security/privacy, especially to one's own territory? This implies power/authority on your own territory. Despite the obvious fact that the world is geographically separated between lands and seas there is another factor why divisions occurs. From our world history we have learned that previous colonizers gives emphasis on colonizing as much land as they can and inculcate their own customs and traditions. Just like what happened in our country (Philippines) we have been colonized by numerous country such as Spain, US and Japan and all tried to inculcate their own into ours. Also, it opened ours eyes to different cultures and such.

The world is divided territorially because this gives sense of security and protection in own's property. Also, with cultural and ideological differences it would be hard to have a unanimous nation. In short, divisions happened because of differences. This gives the authority to each nation to practice their own practices without any restrictions from others beliefs and even if there are nations like Europe (which is compose of different sectors) they still differ from each other.

I guess the division helps us to recognize the differences and boundaries we can make to each and everyone. Also, this helps us to learn from each other and to improve our own with time. Moreover, this organizes or rather maximizes sense of responsibility and limits the upbringing of chaos. But now in the time of globalization, these territories are starting to loosen up because we are all connected easily unlike before. The turn back is that we might forget our ancestral root and eventually make a new civilization in the near future that there will be no more racial biases and such. I am not saying this is not good however, knowing one's ancestral roots and living it up implicates a very important thing