One of the most important differences between Sudan and SA is the degree of racial and ethnic warfare in Sudan. Once a country crosses the line into wholesale ethnic or racial warfare, with widespread killings, atrocities, and disruptions, it is much harder to put the society back together.

SA had years of terrible repression and much violence against the black majority and its supporters. But SA never fell into major racial war. Though the apartheid regime sought to divide the majority population, it did not systematically arm one group to attack the other.

But in Sudan the arming of such groups, the stoking of racial and ethnic competition and, indeed, deep animosities, have been a feature of all of Sudan’s wars.

The very scale of violence and death is massive in Sudan.

Two million people died in the last north-south civil war. About 300 000 died in Darfur in just a few short years.

A second contrast comes with the role of leaders. Leaders matter. SA was blessed in the final years of its transition with the quality of leaders a country gets perhaps once in a hundred years – Nelson Mandela and FW de Klerk.

They each could build upon a vision of a country transformed in which all could live in peace.

This history of leaders in Sudan is different.

South Sudan’s iconic leader, John Garang, who led the south in its last civil war, had a vision of a united Sudan, transformed, with a broad multi-ethnic and multireligious identity that could indeed incorporate the diverse nature of its population.

But on the very dawn of the peace process which he negotiated in 2005, the Comprehensive Peace Agreement, he was tragically killed in a helicopter crash.

With his death much of that vision diminished. There was no fundamental political transformation in Sudan or in South Sudan.

There is another lesson from SA that is very appropriate, indeed essential for Sudan and South Sudan: the responsibility that its leaders not only assumed, but insisted upon, to conduct the negotiations.

In 1992 Mandela telephoned then US President George HW Bush to solicit US support in a debate before the UN Security Council concerning violence in SA. Bush quickly promised such support.

But then he offered Mandela the mediating talents of his Secretary of State, James Baker – three times.

After the third time there was a long pause. Then Mandela said, “And how is Mrs Bush?”

Later, more formally, both Mandela and De Klerk would decline the president’s offer. This was their country, they each said, and it was for them to resolve its deepest problems.

The history of peace in Sudan is much different.

Perhaps because of the depth and viciousness of much of the violence that I have spoken of earlier, but perhaps too because of the attitudes of the leadership involved, international mediation has had to be a major factor in bringing about peace and is today a major, perhaps the key process, that keeps the peace process alive.

No issue ultimately put before the two presidents – Omar Bashir and Salva Kiir – by the AU High-Level Implementation Panel, ably led by former president Thabo Mbeki, has been decided by the presidents.

Without their commitment that it is their responsibility to make these decisions, hard as they may be, ultimate peace between Sudan and South Sudan will be fragile at best. Right now it is fragile indeed.

Another lesson from SA comes from the fundamental change in the political system that was an outcome of the transition.

Today, the question of how both Sudan and South Sudan are to be governed is as much a major issue as it was before.

For the Republic of Sudan, the marginalisation, politically and economically, of people such as in the states of Southern Kordofan and Blue Nile, in Darfur, in the east, has not been resolved.

As Mbeki has pointed out, even after the south’s departure Sudan is a diverse country, diverse in religion, cultures, and political traditions. The governance of the country must reflect that diversity if internal peace is to be achieved.

Instead, conflict has broken out in Southern Kordofan and Blue Nile, and continues at a lower level in Darfur.

Those from these regions waging war against the regime in Khartoum have banded together in what they call the Sudan Revolutionary Front (SRF), committed to forcibly overthrowing the Khartoum regime.

It was Mandela who urged the ANC to take up the armed struggle. But he would later reveal that his goal was not so much to overthrow the regime, a task perhaps too great or costly to be achieved, but to use the armed struggle as a means to bring the government to negotiate.

Like the ANC, which set out its principles for a new SA in the Freedom Charter, the SRF must develop a political platform. It must be a platform, moreover, for inclusion, for bringing all elements of Sudanese society together.

It must be a road map as well, for peace, a pathway for negotiation when the other side is ready to negotiate.

The SRF must see armed insurrection at most as a temporary means, one to be set aside when the time for peace is at hand.

The government of Sudan must equally look for that pathway to peace. It must be prepared to address both diversity and unity, to undertake a constitutional process – as it has promised – that is truly inclusive, open to real and systematic transformation of the way political power is shared and distributed.

It must, as must its opponents, be pledged to human rights and democracy, for without those, not only will transformation be incomplete, but peace still elusive.

Right now, both sides are heavily focused on military struggle. That has to change.

South Sudan faces major challenges of its own.

There are deep fissures in South Sudan society, submerged in the unity forged in the campaign for independence, but now emerging in stark fashion.

Delicate issues of ethnic balance and participation have to be addressed without creating only loose coalitions of ethnic militia.

South Sudan also emerged at independence with the Sudan People’s Liberation Movement (SPLM) in an overwhelmingly dominant position.

SA knows this situation, with the ANC having been in a similar role. But in SA the constitution protects the rights of people and parties and places checks and balances on the use of power. South Sudan is only beginning the development of a new constitution.

The challenge will be to provide for the development of multiparty politics, protection of speech and the media, and in essence the readiness to contain and share power.

n Princeton Lyman was US ambassador to SA from 1992 to 1995, during the transition to democracy, and is now US Special Envoy to Sudan and South Sudan. In an address this week in Pretoria, in recognition of the 100th anniversary of the ANC, he compared the SA transition to the difficult transition still under way in Sudan. This is an edited version.