We live in a likely globalized world in which people share a seemingly borderless space, leading to an increasingly homogenized culture. Whether they are in Beirut, Tokyo, Paris or Washington, modern individuals are supposed to be flexible, mobile and feel at home in the metropolitan area where they settle. However, the 21st century has also witnessed an increasingly strong attraction in the opposite direction. In the midst of a growing cosmopolitanism, we are seeing nationalist, racist and extremist tendencies on the rise around the world and across the political and religious spectrum. 

Tribalism is considered as the human tendency to create groups based on real or imaginary similarities or differences. Members of these groups strive to protect their clique, make sacrifices and defend their "tribe". Tribes can be formed around criteria such as nationality, ethnicity, religion, and dichotomies. Differences can be widely accepted and "objective" or defined by the group itself, for example the view that ISIS has "real Muslims," as being the only people who underpin its specific worldview. To understand tribalism, it is not necessary to know whether external observers view a particular community as a united tribe, but rather whether the collective identity that underlies membership in that particular group becomes so important to the point where members exhibit tribal tendencies.

Tribalism has an evolutionary basis and is rooted in our socio-psychological reality and culture. Our brains are connected to be social and act within a community rather than live in solitude, to protect not only ourselves, but also those who "belong to us" and work not only for our own good, but also for that of the community as a whole. 

Extremists have long exploited our desire to belong to attract marginalized and vulnerable individuals to their group. The current manifestations of terrorism have even been defined as the neo-tribal wave of terrorism. Islamic State and other jihadist organizations, for example, refer to a fraternity of equals and a sense of community in their propaganda that must be protected from external and evil forces by heroic fighters. Similarly, right-wing groups describe nationality or race as a family value and in need of protection from invaders who seek to undermine white culture and rape white women. Once these stories about tribes are effectively woven—creating an external threat that seeks the destruction of the tribe and fosters a sense of urgency to act to ensure a better future for the children of the tribe—tribalism can be used for radicalization. This mechanism can be exaggerated through social media and possible sounding board, as people vulnerable to radicalization can now be found more easily by recruiters; they can create a common reality through instant communication with people with similar views and create links across physical boundaries, so that tribes are truly modern and virtual.

The dark manifestations of tribalism have shifted from the spheres of extremist organizations to the majority, both in social discourse and in the physical realities of our existence. Europe today has about the same physical barriers as it did before WW2, if not more, political polarization between right-wing populist forces, traditional conservative forces and left-wing forces. A relatively small group of extremists committing an even smaller number of terrorist attacks has triggered a domino effect of tribal polarization, which has been accompanied by a growing fear of "the other" due to migration and an erosion of confidence in the political and economic elite. A cycle of mutual radicalization of opinions and deepening of divisions has begun. If this trend continues, it is likely that extremism on all sides will feed.