But the tensions between the countries were soon overshadowed by a brutal civil war that erupted in South Sudan in December 2013, with forces loyal to South Sudanese President Salva Kiir clashing with those backing his sacked vice president, Riek Machar.
The United Nations estimates that more than 2.2 million South Sudanese have been displaced, most of them internally, and says that the country has faced serious food shortages and disease as a result of the conflict.
Last year, an African Union (AU) report documented forced cannibalism, gang rapes and death by burning as among the atrocities perpetrated during the country’s civil war.
Al-Bashir, who has led Sudan for 26 years, became the world’s first sitting president to be indicted by the International Criminal Court when charges were filed against him for alleged genocide and war crimes in Darfur, western Sudan.
Last year, he left South Africa just as a High Court in that country had decided to order his arrest.