President Moon Jae-in became the first South Korean leader to give a speech to the North Korean public when he spoke at the Mass Games in Pyongyang on Wednesday evening.
In his seven-minute long speech, he said the two countries should "become one", as they were before the war.
Mr Moon is on a three-day visit to Pyongyang where he signed a landmark agreement with Kim Jong-un.
The Arirang Games are one of Pyongyang's biggest propaganda events.
Tens of thousands of people take part in intricately choreographed dance and gymnastic displays, which tell stories of Korean history and myths. This year they are celebrating North Korea's 70th anniversary.
Both leaders received a standing ovation from 150,000 thousand citizens when they entered the May Day Stadium in Pyongyang.
"I propose that we should completely end the past 70 years of hostility and take a big stride of peace to become one again," said Mr Moon in his speech, which was broadcast live in South Korea though not in North Korea.
He also brought up the topic of denuclearisation during his speech, calling for nuclear weapons to be removed "permanently".
Andray Abrahamian, a fellow at the Pacific Forum told the BBC: "The speech was clearly tailored to the North Korean audience."
Mr Abrahamian adds that the mood at the stadium would have been "incredibly emotional", saying that the "performances combined with Moon's speech was designed to tug on the heartstrings of the public".
"It really is an emotional appeal by Moon for support in North Korea. I'm sure now his popularity in the North will be unprecedented."
The Arirang Games, which had not been held for several years, are a significant part of North Korea's domestic propaganda, stressed uniformity, a shared history and the almost divine status of the leadership.
Rights groups have in the past accused North Korea of forcing thousands of children to take part.
"The strict training routine for the Mass Games... is dangerous to children's health and well-being," said a 2014 UN Commission of Inquiry report on human rights in North Korea.
The report also added that the games attracted a large number of tourists "who are often unaware of the human rights violations endured by children who are compelled to participated".
In a highly symbolic move, the Korean leaders made a visit to Mount Paektu to conclude the three-day summit.
The mountain holds a central place in Korean mythology and features in South Korea's national anthem and various North Korean propaganda.
Mr Moon also appears to have sparked comment in North Korea by giving a full 90-degree bow to those who had greeted him at the airport.
One North Korean defector told a local radio station that the 90-degree bow was a way North Korea's citizens had to greet their leaders, not the other way round.
He added that the deep bow would have a deep impact on the North's citizens.