2005 Chad attacks
Armed groups attacked villagers in Chad in September 2005. Several dozen were killed, with estimates ranging from 36 to 75. Chad blamed Janjaweed forces in what was allegedly a cross border operation. This and subsequent  operations then led to a deterioration in relations between Chad and Sudan. See also 
 Chadian Civil War (2005–2010)
 Chad–Sudan relations

References

2005 in Sudan
2005 in Chad
Chad–Sudan relations
Attacks in Africa in 2005