Opening the conference, Sheikh Hamad bin Khalifa Al Thani, the emir of Qatar, said: "We feel there are a lot of similarities between South America and the Arab world. Both of us also hope for a better future for our populations and we face many of the same challenges."
Luiz Inacio Lula da Silva, the president of Brazil, said: "The wealth of the Arab world is now becoming a factor of development ... and you have to protect it.
It was the Brazilian leader who first proposed the idea of the Arab-Latin American meeting during a visit to the Middle East in 2003.
"In a few days, the G20 will try to find a solution to confront an unprecedented financial crisis ... they want to know if we are able to come up with genuine ideas that would prevent our countries from social and political disturbances," Lula said.
"It is a unique opportunity for us to introduce concrete ideas for a better global governance."
Speaking to Al Jazeera, Celso Amorim, the Brazilian foreign minister, said direct contact between South America and the Arab world was very important for both sides.
"I think we are living in a globalised world but in a way it was a globalised world of sorts, in which some countries had relations with the centres of world powers and not among or between themselves," he said.
"One of the factors that made the [economic] crisis less serious in Brazil is that we have very diversified trade. With the Arab world it [trade] went from eight billion to 20 billion dollars in three or four years."
The two regions each include a major oil producer, with Saudi Arabia and Venezuela both among the world's top oil exporters.
Trade between the two blocs has almost tripled since the first summit in Brasilia in 2005.
Arab diplomats said the summit will consider creating a joint mechanism of financial co-operation to reduce the impact of the global economic crisis.
Hugo Chavez, the Venezuelan president, proposed a "petro-currency" to replace the dollar, that would have the backing of oil-rich nations such as Venezuela and its Arab partners in Ooec.
"Venezuela supports ... efforts to find an alternative reserve currency," he said.
Chavez said "the hour has come for the final fall of the American empire".
Striking a more measured note, Michelle Bachelet, the Chilean president, said: "This is the time for a global response to the financial crisis. We hope there is fast co-ordination of the G20 meeting.
"We must call on the International Monetary Fund for more democratic governing and to give more funds to the developing banks to be more effective tools to stop the crisis in the countries that most need it."
Regional issues, such as the deadlocked Israeli-Palestinian peace talks and the international arrest warrant for alleged war crimes in Darfur facing Omar al-Bashir, the Sudanese president, were also raised by South American leaders.
The ICC "has no power to take such an action against a sitting president", Chavez said on his arrival in Doha.
"It does so because it is an African country, a Third World country".
He said: "Why don't they order the arrest of [former US president George] Bush. Why don't they order the arrest of the Israeli President [Shimon Peres]?".
But some Latin American leaders refused to show solidarity with al-Bashir. Cristina Kirchner, the president of Argentina, walked out of the official session to avoid being photographed in his company.
Kirchner, incidentally, is seeking support from Arab countries in a renewed dispute with the UK over the Falkland Islands, reports say.
Argentina continues to claim the Falklands, 27 years after the two countries went to war over the South Atlantic islands.