Forty-four groups have been invited to talks in Qatar on Sunday gathering Chad's military junta and armed rebels.
The meeting is a key step in the junta's plans to bring rebels into a national forum that it says will chart the country's return to civilian rule.
Here are snapshots of the main armed groups:
- Front for Change and Concord in Chad (FACT) -
The biggest group in terms of fighters and weaponry, the FACT emerged in 2016 from a split in a rebel force called the Union for Democracy and Development (UFDD).
It ranges over is northern Chad, a vast, restive and lawless desert region abandoned to illegal gold miners and gangs of traffickers, but it also runs rear bases across the border in Libya.
It was while leading operations against the FACT in northern Chad last April that iron-fisted veteran president Idriss Deby Itno sustained fatal wounds.
His son, General Mahamat Idriss Deby Itno, took over the country, fronting a 15-member military junta.
In the following weeks, the armed forces killed several hundred rebels and took nearly 250 prisoner and the FACT retreated into Libya, according to the authorities.
The FACT's leader is Mahamat Mahdi Ali, who studied in France, where he was also a Socialist Party activist.
-Union of Resistance Forces (UFR) -
Created in 2009 from an alliance of eight groups, the UFR draws its fighters mainly from the Zaghawa ethnic group, from which the elder Deby hailed.
They are led by his nephew, Timan Erdimi, who fled to Qatar for a decade after falling into disgrace.
In February 2019, the UFR mounted an attempt to oust Deby by sending a column of fighters in 50 pickup trucks from Libya via Sudan.
They were beaten back by French air strikes, requested by Deby, a major ally in France's anti-jihadist campaign in the Sahel.
The UFR is estimated to have several hundred men, based in southern Libya and northern Chad.
- Union of Forces for Democracy and Development (UFDD) -
The UFDD was created in 2006 by Mahamat Nouri, a former close aide to Hissene Habre, the president overthrown by the older Deby in 1990.
Habre was sentenced in 2016 to life imprisonment by a special court under the aegis of the African Union for crimes against humanity.
Nouri joined up with Deby and for a time became his defence minister before defecting.
In early 2008, the UFDD, with other rebels, reached the gates of the presidential palace in N'Djamena. Supporting the regime, France secured the capital's airport, allowing the army to obtain more ammunition. The offensive was repelled.
In 2019, Nouri was indicted in France for "crimes against humanity" for recruiting of child soldiers in Chad and Sudan.
Incarcerated in Paris in 2019, he was released in 2020 for health reasons.
The Libyan-based UFDD was greatly weakened when it splintered in 2016 and the FACT emerged. In 2019, several hundred UFDD fighters joined the Deby regime.
- Military Command Council for the Salvation of the Republic (CCMSR) -
The CCMSR was formed in June 2016 after a rift in the FACT.
In a report issued in December 2019, UN experts on Libya said the CCMSR was "most likely steeped in criminal activities and trafficking of all kinds, linking southern Libya to the Tibesti region in Chad".
Chadian rebel groups are also regularly accused of selling their services as "mercenaries" to the two rival powers battling for control of Libya.