South Sudan emerged into the world as a new nation less than a year ago and already it is at the brink of war with its archenemy Sudan, with soldiers from both sides carrying out incursions and Sudan bombing the south with warplanes. But history shows that nascent nations often are plagued by troubles, while others have relatively easy early lives. Some fairly recent examples:

East Timor was a Portuguese colony for more than four centuries before Indonesian troops invaded in 1975. When it voted for independence in 1999, withdrawing Indonesian soldiers and militia went on a rampage, killing up to 1,500 people and destroying East Timor's limited infrastructure. The U.N. poured billions of dollars into the new nation and deployed thousands of troops but after scaling back — too early, critics say — gang violence and splits in the army and police turned deadly. It led six years ago to the collapse of the government and the return of international peacekeepers. Today, East Timor remains desperately poor and its institutions weak. But a successful presidential election earlier this month — the third since the nation of 1 million was born — is widely seen as a sign of growing political maturity.

In 1991, Slovenia fought a brief war for independence from the Serb-led Yugoslavia when former Serbian strongman Slobodan Milosevic decided to let it go. It was the first ex-Yugoslav state to become an European Union member in 2004, and still is the most prosperous of the former six Yugoslav republics.

Bosnia was the scene of the bloodiest carnage as Yugoslavia fractured, and the worst in Europe since World War II. More than 100,000 people were killed and millions left homeless during the 1991-95 civil war in Bosnia. The war ended with a U.S.-brokered peace agreement between Bosnian Muslims, Serbs and Croats. The country remains deeply split between the three ethnic groups, preventing Bosnia from getting closer to the EU, NATO and other international organizations.

It took a four-year war with the Yugoslav Peoples Army and local Serbs who refused to live in an independent Croatia before Croatia became a nation. Some 10,000 people were killed and hundreds of thousands left homeless. It liberated the territory in 1995 by chasing ethnic Serbs out of a pocket in western Croatia in an offensive. Two Croatian generals were convicted by a U.N. war crimes tribunal for their role. Croatia is slated to become the 28th EU member in 2013.

Macedonia was the only ex-Yugoslav republic that split peacefully in 1991, but its name has been a sticking point with Greece that has created a roadblock to its joining the EU. Athens argues that the name Macedonia implies territorial claims against the northern Greek province of the same name, and has also blocked the country's efforts to join NATO. Macedonia has a restive Albanian minority that adds to ethnic tensions and occasional flare ups.

Independence-seeking Kosovo Albanians fought a 1998-99 war for independence from Serbia. The clashes stopped only after NATO warplanes bombarded Serbia for 78 days in 1999. The former Serbian province unilaterally declared independence in 2008. Serbia, Russia, China and the Serb minority in Kosovo do not recognize Kosovo's statehood, which was supported by the United States and most EU countries. Since it is not recognized by a majority of world states, it is not a U.N. member. Some 5,500 NATO-led troops are still deployed in Kosovo to prevent clashes between majority Kosovo Albanians and the Serbs who control a tense northern area on the border with Serbia.

Lithuania, Latvia and Estonia, which had been Soviet republics for a half-century, regained their independence in 1991 after considerable agitation but little violence. Strong independence movements arose in the late 1980s and conducted large demonstrations and acts of resistance. Soviet troops killed 14 people when they tried to take control of the broadcasting tower in the capital of Lithuania in January 1991, and at least seven people died in confrontations with troops in Riga, Latvia, the same month. The coup attempt against Mikhail Gorbachev weakened Soviet control and by the end of August the Kremlin let the Baltics go their own way.

Georgia, Azerbaijan and Armenia suffered bloodshed both before and after the 1991 collapse of the Soviet Union gave them independence. Soviet troops killed about 20 pro-independence demonstrators in the capital Tbilisi in April 1989. Just days before the Soviet Union's formal disintegration, Georgia's president was deposed in a bloody coup and the country plunged into both a civil war and conflicts with the separatist regions of Abkhazia and South Ossetia lasting until 1995. In Azerbaijan, some 130 nationalists were killed in clashes with Soviet troops that had been sent into the capital Baku in January 1990 after anti-Armenian pogroms that killed at least 90. The republics' militias and troops were meanwhile fighting over Nagorno-Karabakh, an ethnically Armenian region in Azerbaijan. That escalated into a full-scale war after independence.