Hundreds of North and South Korean relatives are seeing each other for the first time in decades, at a reunion for families separated by the Korean War.
More than 100 mostly elderly South Koreans arrived in the North on Thursday for the event.
The reunions, which come after North Korea called for better relations between the two sides, will take place from 20 to 25 February.
They come ahead of planned US-South Korea drills, which begin on Monday.
North Korea had earlier threatened to cancel the reunions if the military exercises went ahead.
On Thursday, 82 elderly South Koreans, accompanied by 58 family members, left for North Korea by bus.
More than a dozen of them were in wheelchairs, and two travelled in ambulances as they needed medical attention, AFP news agency reported.
They carried gifts, including clothing, medicine and food for their relatives.
They met their North Korea relatives at an emotional event in the North's Mount Kumgang resort on Thursday afternoon. The families are also scheduled to have dinner together.
Around 180 North Koreans attended the reunion, reports said.
'A true miracle'
One of those selected for the reunions was South Korean Lee Du-young, who is in his late 70s.
"It's hard for people to understand what it's like when you've been separated so long," he told the BBC before he left for the North.
"But it's a true miracle; I'm so elated. All that was missing in my life was my brother, and now that I can see him again, I'd have no regrets whatsoever if I were to die tomorrow."
He said that as well as warm clothing, he would buy his brother chocolate biscuits because he heard they were sought-after treats in North Korea.
The reunions are brief events. Families from both sides meet for a number of hours, before eventually returning to their respective homes.
Only 100 or so relatives are chosen to take part each time. South Korea uses a lottery system to help determine who is to be included.
The process in North Korea, on the other hand, is more opaque, with critics saying Pyongyang plays politics with the families involved.
North Korea has in the past cancelled the reunions after the South took actions it opposed - most recently in September.
The South Korean relatives were briefed before the reunions and were told not to talk about politics.
Many people were separated from their relatives by the division of the Korean peninsula after the 1950-1953 war.
The Korean War ended in a ceasefire, not a peace treaty, and there are no direct means of communication for most North and South Koreans.
About 72,000 South Koreans are on a waiting list to join the family reunion events. Nearly half of them are over 80.
The reunions are the only legal way for families separated by the division of the country to see each other, the BBC's Lucy Williamson reports from the southern side of the Korean border.
They are a small but significant sign of better relations between the two Koreas, but for many of those not chosen this time, the benefits they offer are slow to arrive, our correspondent adds.
In 2010, the programme was suspended after the North's shelling of a South Korean border island.