Ali Muhammad Ali Abd-al-Rahman is accused of overseeing thousands of pro-government Janzawid fighters responsible for the persecution, killing, rape and torture of thousands of people during the height of the 2003-2004 violence.
“I am innocent of all these charges,” Septuagintian Abd-al-Rahman told the judges after reading the charges at the beginning of his trial.
Abd-al-Rahman, whom prosecutors say was also known as Ali Kushayb, voluntarily surrendered to a Hague-based court in June 2020 after a 13-year runaway. He has denied the allegations.
The trial comes amid a rise in what communal violence humanitarian groups have said in Darfur since the end of the UN and African Union missions.
After the worst fighting in decades, 1.6 million people are still internally displaced in Darfur, UN estimates.
The conflict in Darfur first began when most non-Arab rebels took up arms against the Sudanese government, which responded with a counter-insurgency.
Khartoum organized mostly Arab militias, known as Janjaweed, to quell the insurgency, sparking a wave of violence that Washington and some activists said amounted to genocide.
The United Nations estimates that 300,000 people have been killed and more than 2 million have been displaced from their homes.
Abd-al-Rahman has been charged with 31 counts of war crimes and crimes against humanity and could face up to life in prison if convicted.
During the previous hearing, his lawyer argued that the accused was a victim of misidentification and was not educated enough to understand the orders he was carrying out which could lead to war crimes.
Former Sudanese President Omar Hassan al-Bashir, who is facing ICC charges for genocide and other atrocities in Darfur, was ousted in 2019 and is being held in Khartoum.