In some cases, some minority groups may be perceived as impediments to nation-building, unable to blend into a single national identity. Here 'ethnic cleansing' becomes a solution to national integration (UNHCR, 1993; Keely, 1996). According to Keely, this may be achieved through mass population transfer as in the case of Greece and Turkey after the First World War and the case of India and Pakistan after they were divided. In the case of more violent ethnic cleansing, forced expulsion is employed as in Yugoslavia where ethno-national wars erupted from 1991 to 1995. This resulted in a massive flow of refugees. See figure 2 below.