- Troops enter -

Fighting begins on November 4, 2020 when Ethiopian Prime Minister Abiy Ahmed orders a military response to what he calls a "traitorous" attack on federal army camps in Tigray.

He blames the attack on the regional ruling party, the Tigray People's Liberation Front (TPLF), which dominated Ethiopian national politics for nearly three decades before Abiy took office in 2018.

The TPLF denies responsibility and says the reported attack is a pretext for an "invasion".

Two days later, with fighting intensifying, Abiy sacks the head of the military, whose top brass includes many battle-hardened Tigrayans.

On November 9 Ethiopia carries out more air strikes in Tigray with Abiy saying the operation will be over "soon".

- Fleeing to Sudan -

Tens of thousands of refugees flee to neighbouring Sudan as the African Union follows the United Nations in demanding an end to the fighting.

As the refugee flow swells tensions mount between the two countries, whose frontier is disputed.

- 'War crimes' -

After 10 days' fighting, the UN warns of possible war crimes in Tigray.

Neighbouring Eritrea -- with which Abiy signed a peace deal in 2018 that helped him win him the Nobel Prize Prize -- sends troops into Tigray to help Abiy although their presence is denied by Addis Ababa.

- Capital falls -

Two weeks later, having rejected peace talks, Abiy says government tanks are advancing on Tigray's capital Mekele.

The city comes under heavy shelling on November 28 before Abiy announces that military operations in Tigray are "completed".

- 'Ethnic cleansing' -

In February 2021 Amnesty International says Eritrean soldiers killed "hundreds of civilians" in November in the holy city of Axum in Tigray.

The following month AFP documents another massacre by the troops in Dengolat.

US Secretary of State Antony Blinken later urges Eritrea to withdraw and describes violence in western Tigray as "ethnic cleansing".

- Atrocities admitted -

For months Ethiopia and Eritrea flatly deny the involvement of Eritrean forces in the conflict.

But on March 23 Abiy admits that Eritrean troops had crossed the border into Tigray.

He also suggests they may have been involved in atrocities against civilians.

The next day the Ethiopian Human Rights Commission says Eritrean soldiers massacred over 100 civilians in Axum in November.

- Withdrawal? -

After admitting Eritrea's role, Abiy flies to its capital Asmara to meet with Eritrean President Isaias Afwerki.

During the visit Abiy says Eritrea has agreed to pull its forces out.

Just over a week later Ethiopia says Eritrean troops have "started to evacuate" Tigray but on April 15 the UN says there is no evidence of withdrawal.

- 'Humanitarian disaster' -

As international outrage mounts, AFP obtains government documents showing that Eritrean troops are looting and blocking food aid.

US President Joe Biden in late May calls for a ceasefire and declares that human rights abuses "must end".

In June the World Food Programme says four million people face a food crisis in Tigray, including 350,000 risking famine.

- UN 'deeply disturbed' -

The UN High Commissioner for Human Rights Michelle Bachelet says on June 21 she is "deeply disturbed" by reports of "serious violations" in Tigray and says she has "credible reports" that Eritrean soldiers are still operating in the region.

Elections are held across much of Ethiopia that day but there are no polls in Tigray because of the conflict.

- Bloody market airstrike -

At least 64 people are killed on Tuesday and 180 injured in an Ethiopian airstrike on a market in Togoga, according to a toll released on Thursday.

The attack was aimed at rebel fighters, Ethiopia's military insist.

The UN calls for an urgent investigation.