Some fought as guerrillas during the bloody Balkans wars of the 1990s, battling powerful tanks and artillery.
Others grew up under the influence of radical Islam that has gained ground in poverty-hit areas in the Balkan countries and regions populated by Muslims.
Today, both experienced fighters and their younger followers are leaving the Balkans to join Syrian rebels on the front line. Many return home in body bags with their families often unaware they had even joined the fight.
Migena Maliqaj, an Albanian, had not heard from her husband Halil since November, when he told her he was leaving their home in Prush, outside the capital Tirana, to try to find work in Turkey. In June, she received a text message from an unknown number saying that Halil had been killed in Syria. Maliqaj was reluctant to talk to AFP.
“Leave me alone, I do not know anything,” she said in a trembling voice, pushing her three children inside a two-storey house.
The first Ermal Xhelo's mother knew of her son's involvement in Syria was when the 35-year-old's remains were brought home to her in Albania's southern city of Vlora. He too had said he was going to work in Turkey.
The Xhelo family also refused to talk. “My son had nothing to do with extremists,” the mother told AFP, abruptly ending the phone call.
Illir Kulla, a security expert from Albania, estimates that “at least 300 Albanians from Albania, Kosovo and Macedonia have left for Syria to fight in the name of a 'sacred war’” over the past months. Their conviction comes from their Islamic faith, Kulla stressed.
“They are not mercenaries, but volunteers convinced that they are fighting for a good cause... prone to religious manipulation that the war in Syria is truly a sacred war,” Kulla said.
A classified intelligence report by Kosovan security services described “Islamic extremists” going to Syria in small groups “claiming they are helping out their brothers.”
They travel in “small groups of two or three, in order not to look suspicious,” said the report seen by AFP.
In May, street signs in Novi Pazar, the main town in Serbia's Muslim-majority southern region of Sandzak, were covered with obituaries for Eldar Kudakovic, a 27-year-old killed in Syria during a raid by rebels on a prison near the key city of Aleppo, reportedly with another man from the area.
“All of us are with them. And all of us are Mujahideen,” read a message posted on a Sandzak radical Islam web portal, praising the victims as “martyrs.”
Why should we hesitate to help?
Since the start of hostilities 28 months ago, more than 100,000 people, mostly civilians, have been killed in Syria, the UN says. Millions more have been forced by violence to flee their homes.
Thousands of foreign fighters have flocked to Syria to join rebels fighting to bring down Bashar al-Assad's regime, travelling across the Turkish, Iraqi, Jordanian and Lebanese borders into the strife-torn country.
While many of Syria's rebels started off as inexperienced fighters, they have to an extent benefited from the experience of radical Islamists, many of who had already fought in other wars.
Jihadists have travelled to Syria mainly from Arab states -- Saudi Arabia, Tunisia, Libya and Iraq in particular -- but also from across Europe, the Caucasus and south Asia. Reports of jihadists dying in Syria have not deterred Balkans fighters.
One father-of-three from Podujevo, a small town in northern Kosovo, was making the final preparations for his journey to Syria, which he was to enter illegally.
“If Russia, Iran and Hezbollah do not hesitate to defend (President Bashar) al-Assad's regime which murders its own citizens, even children, why should we hesitate to help the Syrians?” argued the 40-year-old, a jobless construction worker who wanted to remain anonymous.
His words muffled by the call for noon prayer from a nearby mosque, he was nevertheless adamant his decision was final.
“Once I am gone, I will not return until the end of the war,” he told AFP, adding that his wife and young children would be taken care of by his two brothers.
Also planning to depart for Syria was a former sniper in the ethnic Albanian Kosovo Liberation Army, the separatist guerillas which fought against then Serbian strongman Slobodan Milosevic's forces in the 1998-1999 war. After spending two weeks in Aleppo to “assess the situation,” he now planned to join the rebels along “with about a dozen war comrades, experts in different weaponry if peace talks fail.”
Religious expert Visar Duriqi said recruitment of future fighters has been taking place in Kosovo through a set-up allegedly run by a Salafi sect known for its strict approach to Islam.
Recruitment is voluntary, experts agree, with Salafists meeting far from the eyes of the community, and often late at night. The Islamic Community of Kosovo, a body representing Muslims, denies any involvement in the Syria recruitment.
“I am all for helping the (Syrian) people to escape from this bloody mess, not individually, but as it was done in Libya” with help from the international community, its representative Resul Rexhepi said.
Observers say that the worsening economic crisis in the Balkans -- compounded by an unemployment rate that tops 20 percent in most countries in the region -- has contributed to the radicalization of youth.
Experts believe that the Salafist presence is strongest in Bosnia, as many foreign fighters joined Muslim forces against Bosnian Serb troops and settled there after the bloody 1992-1995 war.
Esad Hecimovic, a Bosnian security expert, told AFP that volunteers for the war in Syria said they were motivated by the fight for what they describe as a single “Islamic homeland.”
“This is the original motive, the same one which motivated some foreigners to come and fight in Bosnia, and now motivates Bosnians to go to Syria,” Hecimovic said.