Three Singaporeans completed their national service last December and decided to embark on a journey lasting some 170 days, partly following in the footsteps of ancient Silk Road traders.

Mr Boh Ze Kai, 20, and his friends, Mr Atsushi Yamaguchi and Mr Jeremy Ng, both 21, planned to travel from Singapore to China through South-east Asian countries, before crossing Central Asia to Iran and then cutting through Eastern Europe to final destination Moscow.

Their onward journey, which started on Jan 26, is to be made without any flights, but they will fly back to Singapore in June or July.

The trio had been on the road for three months when their journey hit a snag late last month.

They were stranded in Georgia, at the border of Europe and Asia, without their passports for 14 days until last Tuesday. Their passports had been kept by the consular office in Tbilisi to facilitate their application for Russian visas.

Mr Boh told The Sunday Times: "So with the delay in Georgia, we lost 15 days from our original plan. This was offset by eight days of prepared buffer time, but we still had to move seven days faster.

"We were planning to visit only Tbilisi in Georgia, but ended up seeing almost all of Georgia, including somewhat obscure mountain villages with great scenery in Svaneti."

The young men have so far visited over 40 provinces and cities in more than 10 countries, on modes of transport ranging from boats to horses. They now have to cut short their visits to other countries, likely skipping Transylvania in Romania.

The delay in Georgia was just one of the unexpected turns that they had to navigate so far.

Another was an intimidating encounter in Central Asia.

"We were crossing the Kazakhstan border into Uzbekistan when one of the guards approached me and accused me of being a terrorist, because I had a (body) piercing and dyed hair. He called another guard, who demanded presents or he would not let us pass," recounted Mr Boh.

They were allowed to enter after Mr Boh said he was Buddhist and gave a 100,000 Vietnamese dong (S$6) note to the guard.

The trip had been inspired by Mr Boh's interest in the Silk Road. He wanted to experience what it was like for people in the past to travel through the Silk Road.

The former Raffles Institution (RI) student gathered Mr Ng and Mr Yamaguchi, also from RI, and they planned what will be almost half a year of travel, with a budget of $8,000 for each person.

Unexpected delays aside, all three of them have been struck by how friendly most people they met were. Said Mr Ng: "They don't expect anything from you. They just want you to share life experiences with them, to know more about the world."

For example, they were on a train in China, surrounded by farmers and mounds of fertiliser, when a farmer began a conversation with them on Chinese land reform.

In Iran, they met an ice cream seller who insisted that they stay over at his house. When they politely declined and said they were moving on to Tabriz, he said, "My brother lives there. Go stay at his house; here's his phone number."

The trio have had to battle fatigue and endure 20-hour bus rides. They also faced obstacles such as bad weather, illness or trouble with the authorities.

"I had two major cases of diarrhoea, so the two others had to babysit me," said Mr Yamaguchi.

But they took care of one another and took on different roles.

Mr Boh, who speaks eight languages, including Russian and Turkish, said: "Jeremy is in charge of safety and insurance coverage, Atsushi handles fitness plans throughout the trip to keep us healthy and looking good in photos, while I work on pre-trip logistics like visas, and languages."

Despite the long trip, their families did not have objections.

"My dad was more concerned about how we funded our travels," said Mr Ng. "We decided to use money earned from NS."

Mr Boh's mother Yeo Sue Ann, 51, a housewife, said: "My primary concern was safety, so I asked (Ze Kai) to change some destinations. This is not his first time travelling, so I think he can manage. But I think I will be stressed if I don't hear from him for three days."

On the insights they have gained so far through their travels, Mr Yamaguchi said he was able to see various countries for himself, to see how different they are from the way they are portrayed in the media.

Mr Boh added: "Sometimes, we pity people because of what we think their society lacks. We think it would make them unhappy, but that does not translate into reality.

"Also, there is the cultural relativity of everything: What is acceptable or moral in one country might not be in another."

Now in Turkey, the trio are moving on to countries like Bulgaria, Romania and Hungary.

An account of their journey can be read on exercise silkroad.wordpress.com, while photos of their trip can be viewed on Instagram @exercisesilkroad.