Ethiopia's reformist new Prime Minister Abiy Ahmed arrived in Eritrea's capital and a live broadcast by Eritrean state television showed President Isaias Afwerki greeting him at the airport in scenes unthinkable just months ago. But the two countries share close cultural ties.
Rwandan President Paul Kagame, the current chairperson the African Union, praised their courage, saying on Twitter that they were "doing the right thing for their people".
Ethiopia's Prime Minister Abiy Ahmed is welcomed by Erirea's President Isaias Afwerki as he disembarks the plane. But we can assure you we will face the future together. Eritrea achieved independence from Ethiopia amicably in 1993 but the two countries swiftly became bitter enemies. Observers of the diplomatic thaw have asked whether peace with Ethiopia would lead Eritrea to loosen up and drop its long defensive stance.
Images of both men hugging took the continent by the storm, trending all day on social networks.
The United States' chief of mission in Asmara tweeted photographs of smiling Eritreans waving to the motorcade carrying the two leaders.
"A new era of peace and friendship has been ushered [in]". He said the Ethiopian leader's visit was "history in the making" and had "set the tone for rapid, positive changes". "The yearning for peace was palpable and we'll decidedly move forward for the good of our people", he tweeted on Sunday.
Ethiopia and Eritrea officially declared an end to a two-decades-old war on Monday, a day after their leaders held a historic summit in the Eritrean capital Asmara. In early June, Ethiopia announced it would honor all the terms of the 2000 peace deal, suggesting it might be ready to settle the border dispute.
Last month a high-level delegation from Asmara visited Addis Ababa for the first time since 1998, when conflict erupted over their disputed border.
Ethiopian and Eritrean leaders formally restored relations Monday, ending 20 years of enmity, and citizens from both counties immediately began phoning each other to get back in touch.
Abiy said the two leaders have "agreed to bring down the wall between us". While the visit had been rumoured for weeks after lower-level meetings, it still astonished those who have endured almost 20 years of cold war and conflict.
Abiy said they had agreed to re-open embassies in each other's capitals, and that his landlocked nation of 100 million would begin using a port in Eritrea, which is on the Red Sea. He did not identify which port.
The global boundary commission later decided that Badme, a borderland that was a flashpoint of the conflict, belonged to Eritrea while it ruled that Eritrea should compensate Ethiopia for the huge amount of Ethiopian shipment confiscated in Assab Port.
Abiy has also pardoned dissidents, lifted a state of emergency and promised to partly privatise important state-owned firms.
The shake-up by Abiy, a polyglot former soldier from the Oromo ethnic group, Ethiopia's largest, has won plaudits from Asmara to Washington and drawn comparisons to the 1980s "perestroika" reforms of Soviet leader Mikhail Gorbachev.