More than a dozen were in wheelchairs and needed help boarding the buses, which they shared with 58 family members, brought along for physical as well as emotional support.
After crossing the world's last major Cold War frontier, there was another 30-kilometre drive to a resort on Mount Kumgang -- the venue for the emotional reunion with 180 North Korean relatives they have not seen for more than 60 years.
"I think when I see her face, I won't believe it's real," Kim Dong-Nin, 81, said of the elder sister he left decades ago in Pyongyang.
"I wonder if I will be able to recognise her immediately? It's been so long," Kim said.
All carried bags stuffed with gifts, ranging from basic medicines, to framed family photos and packets of instant noodles.
Some brought bags of fresh fruit which they planned to offer in a joint prayer ceremony with their reunited siblings to their late parents.
The five-day reunion event at Mount Kumgang was the result of tortuous, high-level negotiations between Pyongyang and Seoul, which nearly broke down over the North's objections to overlapping joint military exercises between South Korean and the United States.
Millions of Koreans were separated by the 1950-53 war, and the vast majority have since died without having any communication at all with surviving relatives.
Because the conflict concluded with an armistice rather than a peace treaty, the two Koreas technically remain at war and direct exchanges of letters or telephone calls are prohibited.
The reunion programme began in earnest after a historic North-South summit in 2000, but the waiting list has always been far larger than the numbers that could be accommodated.
For many, time simply ran out, and last year alone 3,800 South Korean applicants for reunions died without ever seeing their relatives.
For those who drove to Mount Kumgang on Thursday, the moment they have longed and prepared for over the years will finally come at a mass reunion gathering in one of the resort's main halls at around 3:00pm.
There will be a dinner in the evening and then private reunions between the divided relatives on Friday.
For all the joy the reunion brings, it is tempered by the realisation that, with an average age of 84, the farewell on Saturday will be final.
"This will be our first and last reunion," Kim Dong-Nin acknowledged, shaking his head.
All the South Korean participants had spent the night in a Sokcho hotel, where they were given an "orientation" course by South Korean officials listing a series of dos and don'ts for their stay in Mount Kumgang.
"They were basically telling people not to discuss any political issues and not to be swayed by North Korean propaganda," said Kim's wife, Shin Myung-Soon.
The Kumgang event will be the first reunion since the programme was suspended following the North's shelling of a South Korean border island in 2010.
A reunion had been planned at the same venue for last September, but was cancelled at the last minute by North Korea.
The emotional meetings with 180 North Korean relatives will last until Saturday, after which the South Korean group will return home.
Then a selected group of 88 North Koreans will travel to Mount Kumgang to meet 361 of their relatives from the South from Sunday to Tuesday.