When a person is treated as if he or she is not there even when he or she is alive, that level of ostracization is called “social death.” If violence is the capacity to harm, then ultimate violence means obliteration. Killing a person is obviously one grave way to disempower someone ultimately. At the individual level, killing a person is an extreme form of disempowerment. Yet, because people matter to others, cruel people might attempt to obliterate a person even more, such as by mishandling a corpse, destroying the person's effects, and denying the memory and contributions of the murder victim, effectively erasing that person’s existence and mattering. From a Power Basis Theory perspective (Pratto et al., 2011), obliteration eliminates individuals' legitimacy, their care of others, their obligations, and others' obligations to them.
At the intergroup level, ultimate violence is genocide, as it is commonly called (Click for related definitions and historical data). The Nazi genocide is infamous for its mechanistic nature and scope. Ahram (2014), though, cautions that we should not take that and other examples to assume that it is mostly nations that actually commit genocide. Rather, he documents that small armed groups often carry out the genocidal intentions of governments, and that small groups also have originated a number of genocides.
As with individual killing, the definition of genocide goes beyond the mass physical killing. It includes processes that attempt to erase the existence of the people. For example, destroying cultural artifacts, language, music, religion, customs and the history of a people are acts of genocide. For example, both the U.S. and Canadian governments separated families, suppressed religious and cultural practices, use of languages, and gatherings in their genocides against indigenous people (e.g., BIA speech and U.S. genocide; report re Canada's genocide against First Nations; boarding schools in U.S. & Canada). As another example, in his 2007 book, The ethnic cleansing of Palestine, Israeli historian Ilan Pappe describes many ways that Israelis have effectively erased their collective memory of the existence of Palestinian people on their land, for example, in nature parks that fail to point out the extant remnants of Palestinian homes' foundations, and almond trees and other plants that were cultivated, not wild.
In addition to the personal connections any human being has to others, communities are valuable as the social ecologies in which we function. It is no wonder that groups who have been systematically subject to pogroms, forced migration, murder and other kinds of violence and subjugation react by being very assertive of their groups' culture and identity. They are trying to restore a beloved community, which is necessary for belonging, and restore what might otherwise be their group's death. This helps us understand why forgetting and denying genocide, or calling it by milder names, may feel like genocide all over again to survivors and their progeny. For example, you could easily find hurtful and preposterously false claims on the internet by anti-Semitic bigots that the Nazi genocide against Jews (and others) did not occur.
The legitimacy of a community is at stake in conflicts over the reality of genocides, forced migrations, and other means of attempting group obliteration. For example, some Palestinian families treasure the house key from their former family home that is now occupied by Israelis. The house key is a potent symbol for Palestinians of where they once lived (Webster, 2016) and might suggest the right of return (Khalidi, 1992). (I list some websites that help explain, below). You could also easily find anti-Semitic websites suggesting that Palestinians' house keys are false and denying their history in historical Palestine. On the illogical assumption that a group which is a victim cannot also be a perpetrator, groups sometimes engage in these contests over legitimacy by each claiming to be victims, and victims only-- a phenomenon recently identified as competitive victimhood (Noor, Schnabel, Nadler, & Halabi, 2014).
Ahram, A. I. (2014). The Role of State-Sponsored Militias in Genocide. Terrorism and Political Violence, 26, 488-503. https://doi.org/10.1080/09546553.2012.734875
Khalidi, R. I. (1992). Observations on the right of return. Journal of Palestine Studies, 21, 21-40. https://doi.org/10.2307/2537217
Noor, M., Shnabel, N., Halabi, S. & Nadler, A. (2012). When suffering begets suffering: The psychology of competitive victimhood between adversarial groups in violent conflicts. Personality and Social Psychology Review, 16, 351-374. https://doi.org/10.1177/1088868312440048
Pappe, I. (2007). The ethnic cleansing of Palestine. Oxford: Oneworld.
Pratto, F., Lee, I., Tan, J. & Pitpitan, E. (2011). Power Basis Theory: A psycho-ecological approach to power. In D. Dunning (Ed.), Social Motivation (191-222). New York: Psychology Press.
Webster, S. (2016). Post-domicide artefacts: Mapping resistance and loss onto Palestinian house keys. Cultural Studies Review, 22. https://doi.org/10.5130/csr.v22i2.4726
Here are some recommended websites with photos and commentary about the Israeli destruction of Palestinian homes and the meaning of keys and their representation as a Palestinian symbol.