I wouldn't fully blame Oromia. The root cause was the referendum, that was set-up in a way that only could set a precedent of never-ending conflicts. Basically one of its kind, where you were voting practically village-by-village. Then you have two clans who have lived with each other long enough, to not have any clear boundaries between them. Geri were for DDS, while Jarso were divided, mostly for Oromia. (They are Somalized Oromos who identify with Somali-Dir and/or Oromo-Afran Qallo clans, depending on which Jarso and when you ask them).
As soon as the results were announced, all hell broke loose. Not all people in the area even voted, because having a vote through democratic means, was foreign to them. Some of the results were not even accurate. But half of the former region would be split between DDS and Oromia.
Since then, no one has even attempted to find a solution on how to properly implement the results, even though most have accepted the results by now. During the last 20 years, endless fightings, massacres, state violence (from both DDS and Oromia). At this point, most Jarso are united in being for Oromia, which complicates things further.
In any case, through all of this and by now, most Geri have left Jinacsani and likewise with Jarso in Tuli Guleed. Most of the lands left are currently still 'deserted'. But the region, is very resource rich in terms of water and being fertile land. And Oromia is focused on developing it now, which will probably mean more 'land grab'.
Now with this DDS gov't, who is largely subtile in its actions and refraining from doing anything. While Oromia is more bold and taking actions, despite mostly no consensus with the DDS gov't. But with a Jarso significant area, they are free to do anything. While the Somali land, that they wrongly control/took over, we (the locals) can't do much, with limited help from Cagjar.