The center of Sudan’s brutal civil war has shifted west as fighting between the army and paramilitary forces intensifies.

The Sudanese Army drove the paramilitary group, known as the Rapid Support Forces (R.S.F.), from central Khartoum, the capital, in March. Since then, the R.S.F. has turned its attention to the western Kordofan region, and Darfur, where it already controls most territory, except El Fasher, the only city in western Darfur that is still held by the Sudanese Army.

Now, Kordofan has become a strategic crossroad for both sides in the conflict. If the R.S.F. wants to strike central Sudan again, it has to go through Kordofan from Darfur. And if the Sudanese Army wants to push the war into R.S.F. territory in Darfur, it likewise needs to go to Kordofan.

As the two sides vie for more power in the area, more civilians are being killed in what rights groups say is the world’s worst humanitarian crisis. Taking Kordofan “would shift the momentum of this war quite dramatically,” said Alan Boswell, director of the Horn of Africa project at the International Crisis Group.

The R.S.F. declared a parallel government based in Darfur in April. Last week, the group repelled an organized attack by the Sudanese Army and launched its own strike in North Kordofan state, according to Sudan War Monitor, a research group tracking the war. The R.S.F. detained and executed dozens of military prisoners, the group said.

The United Nations Human Rights Office of the High Commissioner verified the killing of 60 civilians at the hands of the R.S.F. in North Kordofan’s Bara region in July, the group said in a statement. Other estimates place the death toll in the hundreds. UNICEF reported that 35 children and two pregnant women were killed in the violence.