The leaders of the so-called Bric emerging economies have called for more influence - including Russia's speedy entry to the World Trade Organisation (WTO).
The Bric countries are some of the world's fastest-growing economies - China, India, Brazil and Russia.
South Africa is attending the group's annual summit for the first time.
As well as the WTO call, the group has asked for certain changes to the global financial system.
These include a call for the International Monetary Fund to expand its use of Special Drawing Rights (SDRs), which are used as a quasi currency to transfer funds between member governments.
The Brics called for a broad-based international reserve currency system "providing stability and certainty".
A joint communique, termed the Sanya Declaration, said the current system was no longer representative.
"The governing structure of the international financial institutions should reflect the changes in the world economy, increasing the voice and representation of emerging economies and developing countries," it said.
At the summit on the southern island of Hainan, the leaders of Brazil, Russia, India, China and South Africa said the recent financial crisis had exposed the inadequacies and deficiencies of the current monetary order, which has the dollar as the world's most-used currency.
Chinese President Hu Jintao said: "The era demands that the Brics countries strengthen dialogue and co-operation."
These countries are worried about the long-term direction of the dollar because of the US's large trade and budget deficits.
China has been diversifying into euros to reduce its dependency on the value of the dollar.
In a move designed to signal another type of move away from dollar-dependency, the development banks of the five nations agreed in principle to establish mutual credit lines denominated in their local currencies.
The Brics also called for a greater say on the UN Security Council, on which only China and Russia of the group have a permanent seat.
Brics is a term coined by Goldman Sachs investment banker Jim O'Neill to highlight Brazil, China, Russia and India's similarities in terms of their potential for development and growth.
It did not include South Africa.
He told the BBC it was a mystery as to why South Africa had been invited to participate in their meeting: "South Africa is small compared to these countries. South Africa is about half a per cent of global GDP.
"And there are other economies which have much more justification if they were to really look at similar potential to the Brics. Turkey, Indonesia, Mexico, Korea, even Saudi Arabia, Poland. I don't really understand why the Chinese and the others agreed to it."
The four nations have 40% of the world's population and almost a fifth of the world's growth.