Farmers from the Kodo community on Monday attacked Fulani herders camped in the Monts de Lam department, Logon Oriental provincial governor general Ahmat Dari Bazine told AFP by telephone.
He said the Kodos are Chadian "rebels" based over the border in the Central Africa Republic (CAR).
"The Kodos killed two Fulani herdsmen Monday in their camp and wounded six others and lost two of theirs," in the ensuing clashes, the general added.
The Kodos then attacked another village killing four people before gendarmes gave chase.
The gendarmes killed 14 of the attackers, he said, leaving a total of at least 22 dead.
Hassan Khalil, first deputy prosecutor at Baibokum, capital of the Monts de Lam department, confirmed the fighting and the death toll to AFP.
Tension between semi-nomadic Arab herders and sedentary indigenous farmers is a longstanding problem in central and southern Chad, but also in the east where many people are armed.
Farmers accuse herders of pillaging their land with their grazing animals.
Herders typically come from arid regions of the Sahel in northern Chad, seeking to settle on more fertile land for breeding camels and sheep.
But this time, the governor accused the Kodos of being Chadian rebels hiding in CAR, a claim AFP could not independently verify.
"This new strategy is deliberately set up by the Kodos to create problems between herders and farmers, between Muslims and Christian," general Dari Bazine said.
Authorities in Chad and CAR regularly trade accusations of running bases in each other's country for rebels who then cross the porous border to stage attacks.