On a dangerous journey into the unknown, it's the little things that matter most
To survive days on end of walking and improvised camping in harsh weather, they must concentrate on essentials: pain medicine, foot powder and first aid, food and personal hygiene items.
The savviest have smartphones with backup battery power and SIM cards that work in the countries they're passing through. Otherwise, they can end up walking in circles without satellite navigation, particularly at night, when many travel to avoid police.
The tens of thousands of migrants who spend weeks on foot, vehicle and boat traveling to Europe to escape war, persecution and poverty must weigh carefully what they carry with them in their backpacks.
Trekkers crossing the border from Serbia to Hungary shared what they were carrying - and what they treasure the most.
Wafaa Bukai (25), student
Waiting with her brother at a Serbian camp for migrants before the border crossing, Bukai shows a visitor sentimental objects and images from her past in Damascus, Syria.
She explains that she left virtually everything behind with relatives, but requires a few emotional touchstones to keep memories alive.
"My homeland is destroyed and not safe," Bukai says. "I left everything: my home, my clothes, my friends, my family."
Unlike many trekkers, who carry precious photos only electronically on a phone, Bukai thumbs through her album of childhood images, including herself in school uniform and trips with family to the beach.
Perhaps her most prized trinket, while of no monetary value, transports her mind to the vibrant heart of old Damascus, the sprawling Al-Hamidiyah Souq inside the walled inner core of the Syrian capital. It's a simple cowrie shell, purchased as a youth in a market beside the medieval Citadel.
"I remember Damascus everywhere, every town I go to," she says, thumbing the seashell in her hand.
Mohammad Al-Abdallah (36), architectural engineer
"I would never go anywhere without my Koran," says the Baghdad resident, who has spent three weeks traveling with his 17-year-old son, Bashar, from Iraq to the Hungary border via Turkey, Greece and the Balkans. "I pray five times every day. I read by the moonlight."
He opens his backpack and pulls out his palm-sized edition of the Muslim holy book. Its cover is frayed and it is wrinkled from water damage from overnight rains. Some pages stick together and threaten to tear, but al-Abdallah opens the book gingerly and recites a favorite passage to his son.
Bashar tells his father that is too slow. He pulls out his smartphone, launches his Koran app, and finds the same passage in seconds. "My pages never tear," he says.
Mekdad Marey (25), computer graphics designer
The native of Damascus has spent two weeks travelling from a refugee camp in Turkey to the border of Hungary in hopes of making it to Germany. For Marey, Germany doesn't represent merely the strongest economy in Europe; it's also where he thinks his health challenges might be solved.
In his unusually small bag, he carries a wide range of painkillers and, most importantly, a neck brace. He attributes his chronic back pain, including a slipped disc, to long hours at a desk while studying in Egypt and working in Turkey.
"Turkey is good, but the money is little, and I need more money to fix my problems," he says, donning his neck brace, which he uses mostly when trying to sleep in his group's overcrowded pup tent. "I am hoping that medicine is better in Germany, the doctors are better, and they can help me."
Behat Yasin (45), shepherd
The Kurd, who has lived in Syria and Iraq while following his flocks of sheep, says he was fortunate to flee west ahead of the threat from the Islamic State. "Many of my friends, I am sure, are dead," says Yasin, who unlike many travellers has no smartphone or social media skills to keep in touch with home.
He does have his shepherd's tool with him: a long, bone-coloured cane that he once used to tap the rear ends of his sheep. Now he uses it simply to keep himself upright, seven hours into his walk across the border from Serbia to Hungary.
"Now I am the sheep. I just follow the others. I must go faster now," he says in broken German, gesturing ahead to a large group of mostly teenage Kurds he has followed since Turkey.