Rubuta ci gaba don wannan sakin layi - Gabashin Slavonia, Baranja, da Yammacin Syrmia an kafa su ne daga ɓangaren Jamhuriyar tawaye ta Serbian Krajina (RSK) wanda sojojin gwamnatin Croatia ba su mamaye shi ba a watan Agusta 1995. Bayan Operation Storm a watan Agusta 1995, wanda yawancin Jamhuriyar Serbia ta Krajina aka mayar da shi ga ikon Croatia, Gabashin Slavonia, Baranja da Yammacin Syrmia sun zama "de facto" yankuna masu cin gashin kansu. Nan da nan bayan kammala Operation Storm
, Shugaban Amurka Bill Clinton, a cikin tsarin shirin kawo karshen yakin Bosniya, ya ce dole ne a sami ""... wani shiri na dogon lokaci don warware matsalar a Gabashin Slavonia... bisa ga ikon mallakar Croatia da ka'idodin da aka tsara a cikin shirin Z-4". Croatia a wannan lokacin ta yi jinkiri tsakanin mafita ta diflomasiyya ko ta soja, amma saboda tsananin matsin lamba daga kasashen duniya, an yi watsi da yiwuwar shiga tsakani ta soja. A watan Nuwambar 1995, shugabannin Serbia na gida sun rattaba hannu kan Yarjejeniyar Erdut, wanda aka amince da sake hadewar wannan yankin a cikin Croatia. An cimma yarjejeniyar Erdut a matsayin wani ɓangare na shawarwari a taron yarjejeniyar Dayton. Duk da haka, a shekara ta 2007, kungiyar tattaunawa ta Croatia ba ta yarda da shirin Z-4 da Shugaba Bill Clinton ya gabatar a matsayin tushen tattaunawa ba.