The question:

If competition were so severe between members of the same species, then how can primitive states such as tribal societies co-exist with more advanced states of civilization? Wouldn't the more primitive societies have been wiped out by now? Indeed, if they are so primitive, how could they exist at all with so many foreigners transiting their territory?

There are other parts of the world where tribal behaviours exist, and their populations have slowly diminished with exposure to industrial society. For tribal culture to persist it has to be advantageous. The emergence of Islam, a culture which often confines women to the home and prevents them from intermingling with foreigners, may be the key to the success of tribal culture in the Middle East. This allows the local bloodlines to proliferate, even with frequent occupations by foreign armies. A system of oppression is needed to sustain this process, until the descendents of certain families are numerous enough to dominate the territory. Clearly, this was an advantageous adaptation from an evolutionary standpoint, favoring those who can oppress and possess the largest number of women for the sole purpose of reproduction.

Western freedom directly counteracts this process. However, exposing their culture to an occupation by western forces will almost certainly immunize them further, and may allow their culture afterward to infiltrate ours, through open immigration, and multi-culturalism. Multiculturalism itself might be considered equivalent to the expression of vestigial cultures, where none have been found particularly useful for survival or reproduction. It might incubate an oppressive culture, allowing it to go unnoticed, to obtain a foothold and increase in numbers. Clearly, this problem is prevented by liberating all women BEFORE ceasing the occupation, and guaranteeing their freedom afterward. Anything less invites a future reversal of fortune.