Suspected members of the Arabic-speaking Misseriya community stormed a village near the disputed Abyei town in South Sudan, set some of its dwellings on fire and killed at least 29 people, news agency Reuters reports, quoting a regional administrator.
The news agency reports 18 others were injured.
Abyei is home to the Dinka Ngok, a subsection of South Sudan's largest ethnic group, the Dinka.
The Misseriya, who are Arab nomads from Sudan, travel through the region as they take their cattle to greener pastures in South Sudan.
The disputed area has oil reserves. Abyei's Dinka Ngoks want to join South Sudan, while the Misseriya favour a union with Sudan.
A United Nations peacekeeping force is in the region as the two countries are yet to agree on its status.