The world has its newest nation – South Sudan, which celebrated its independence with ceremony in its capital, Juba, on Saturday.

A crowd of several hundred thousand roared when soldiers raised the new South Sudan flag and lowered the flag of the north.

Attendees also heard a formal declaration of independence and good wishes from a series of dignitaries, including the president of north Sudan, Omar al-Bashir.

The Republic of South Sudan became the world's newest country at midnight local time. Residents of Juba celebrated with parties in the streets.

The celebration continued with ceremonies at a Juba stadium named in memory of John Garang, who led southern forces during Sudan's long north-south civil war.

The last speaker, South Sudan President Salva Kiir, urged all citizens of the new nation to build a vibrant society and economy. He said following the civil war with the north, South Sudanese must forgive but will never forget the suffering they endured.

U.S. President Barack Obama said in a statement Saturday that he is “proud” to extend diplomatic recognition to South Sudan. He said the country's newly declared independence is a “historic achievement” that shows, in his words, “the light of a new dawn is possible” after war.

Mr. Obama also called on both sides – the northern government in particular – to put an end to violence and intimidation in the northern-controlled state of Southern Kordofan. Intense fighting between northern troops and pro-southern fighters in that state has displaced tens of thousands of people.

U.N. Secretary General Ban Ki-moon also mentioned the recent fighting when he addressed the crowds in Juba on Saturday.

He urged both sides to use the independence celebrations as a moment to declare unequivocally that they remain committed to addressing what he called the “unfinished business” of the 2005 peace agreement.

The 2005 peace deal ended the Sudanese civil war and made possible the January referendum in which southern Sudan voted overwhelmingly to split from the north.

The declaration of independence approved by South Sudan's parliament calls for a system of governance that upholds rule of law, justice, democracy, human rights and respect for diversity.

In the background of Saturday's festivities there are many challenges the new nation will face.

South Sudan has been wracked with deadly tribal and rebel violence, and has yet to resolve disputes with the north on borders and how to share oil revenue.

On Friday, the U.N. Security Council approved a new peacekeeping force for South Sudan. The force will have up to 7,000 troops and 900 civilian police.