Members of the Turkish community protested at the unveiling of a plaque to a genocide they say never happened.
Over a hundred and fifty people protested before the unveiling
The Armenian genocide of 1915 at the time of the Ottoman Empire has been a source of deep division between Turkish and Armenian communities worldwide.
Armenians say 1.5m were killed, through systematic massacres or starvation, a claim denied by the Turkish community.
Saturday's unveiling at the Temple of Peace in Cardiff saw feelings running high on both sides.
Welsh assembly Presiding Officer Lord Dafydd Elis-Thomas was at the unveiling of the plaque which has been paid for by donations from the Wales Armenia Society.
Members of the Turkish community insist that erecting the memorial amounted to racism.
Protestor Levent Hassan said: "It's a question of our ancestors being accused of genocide."
"If such a genocide took place, then let's prove it and let all concerned commemorate those horrible events," he added.
"But if there isn't - why should we allow our ancestors to be slandered in such a way."
The monument stands in the gardens of the Temple of Peace on what is said to be the UK's first piece of public land donated for an Armenian memorial.
Ahead of the ceremony, Welsh assembly Presiding Officer Dafydd Elis-Thomas said Wales's relationship with Armenia "went back centuries".
He received a marble cross, or khatchkar, on behalf of Wales at the unveiling ceremony.
Lord Elis-Thomas joined members of the Armenian and Christian communities on Saturday.
"The fact that the funds for this fine memorial have been raised entirely by the Armenians who live in Wales and that it will occupy a special place here in the Temple of Peace, reflects the vibrant Welsh interest in the history of Armenia," he said.
The Welsh Centre for International Affairs, which is located at the Temple of Peace, is a forum which seeks to promote human rights and international understanding.
Steven Thomas, its director, sad: "We've held events at the Temple of Peace over the past seven years to note the Armenian genocide, including parts of ceremonies we've held for National Holocaust Remembrance Day in January each year. "
However, he said there had been a "much bigger response" to the monument because the commemoration to the Armenians would literally be set in stone.