Complex sentence: Yahad-In Unum (YIU) is a French organization founded to locate the sites of mass graves of Jewish victims of the Nazi mobile killing units, especially the "Einsatzgruppen", in Ukraine, Belarus, Russia, Poland and Moldavia.
Split into simpler sentences: Yahad-In Unum (YIU) is a French organization founded to locate the sites of mass graves. YIU's primary initiative is to locate the sites of mass graves of Jewish victims of the Nazi mobile killing units, especially the "Einsatzgruppen", in Ukraine, Belarus, Russia, Poland and Moldavia.