On June 11, 1999, Josh Hart was 4 years old, while Karl-Anthony Towns was 3. Jalen Brunson and Mikal Bridges, born a day apart, were each 2. OG Anunoby was a month shy of his second birthday. None of the current New York Knicks’ starters were even in kindergarten back then, which was the last time the franchise had clinched a playoff series at Madison Square Garden.

That is, until Friday night, when the Knicks defeated the Celtics 119-81 in Game 6 of the Eastern Conference semifinals at MSG to win the series four games to two. The 38-point margin of victory was the largest in Knicks’ playoff history, surpassing a 36-point win in April 1970. The Knicks had won their first seven playoff games this year by a combined 29 points, including by a combined 12 points in the three previous wins over the Celtics. Still, by midway through the second quarter Friday, the outcome was never in doubt.

The Knicks led by at least 20 points for the final 29 minutes and 10 seconds and by at least 26 points throughout the second half, giving their fans inside and outside of the arena plenty of time to celebrate. And oh, did the long-suffering Knicks’ supporters revel in the victory.

As Bridges walked to the press conference room following the win, Hart showed him videos of fans climbing up light poles. Outside the arena, thousands of Knicks’ fans crowded the streets.

“It’s crazy, man, but great for them,” said Bridges, who joined the team last summer in a trade with the Brooklyn Nets. “I’m happy for them. Obviously I’m new here, but I just know how much New York loves their sports, especially the Knicks. I’m so excited to be a part of it…We’ve got way more to go, but I’m happy for them.”

Anunoby and Brunson led the Knicks with 23 points apiece, while Bridges had 22 and Towns added 21 and a game-high 12 rebounds. Hart, meanwhile, had 10 points, 11 rebounds and 11 assists, becoming the first Knicks player since Walt Frazier in April 1972 to record a triple-double in a postseason game.

“I thought start to finish it was terrific,” Knicks coach Tim Thibodeau said.

It was the first time the Knicks secured a playoff series at MSG since 1999 when they defeated the Indiana Pacers in Game 6 of the conference finals. The next year, the Pacers beat the Knicks in the conference finals, which was the last time New York made it that deep in the playoffs.

On Wednesday night, the teams will resurrect their rivalry from a quarter century ago when the No. 2 seed Knicks host the No. 4 seed Pacers in Game 1 of the conference finals. The Pacers won their first two series in five games apiece, defeating the No. 5 seed Milwaukee Bucks and No. 1 seed Cleveland Cavaliers. The Pacers beat the Cavaliers three times on the road, including a 114-105 clinching Game 5 victory last Tuesday. As such, Indiana will have an eight-day layoff between series.

A year ago, the Pacers defeated the Knicks in the conference semifinals, winning Game 7 at MSG by 21 points.

“It’s going to be a tough opponent,” Hart said. “They push the pace. They run on makes, misses. It’s going to be a huge communication series for us. We’re going to have to be locked in on every possession. We’re going to have to get back defensively. We can build off this game. I feel like our defense in transition (and) our communication was great today. That’s something we can carry into that series.”

Indeed, the Knicks were much more effective offensively and defensively compared with two nights earlier in Boston when they lost to the Celtics by 25 points in Game 5. That was the first game Boston played without star Jayson Tatum, who sustained a ruptured right Achilles tendon late in Monday night’s Game 3 and underwent surgery a day later.

On Friday night, the Celtics showed how much they missed Tatum. They tied the game at 16-all late in the first quarter on a Kristaps Porzingis 3-pointer. But the Knicks outscored the Celtics 48-21 the remainder of the half and led 64-37 at intermission.

How confident was the MSG crowd? As Celtics forward Jaylen Brown stood at the free throw line with 3:29 left in the first half, fans began screaming.

“Knicks in 6!,” they shouted. “Knicks in 6!”

At the time, the Knicks were up 51-30, a healthy lead but not an insurmountable one. In fact, the Knicks had overcome 20-point second half deficits in Games 1 and 2 in Boston and won both. Still, the Celtics were overmatched on Friday.

During the first half, the Celtics shot 14 of 42 (33.3%) from the field, including 4 of 19 (21.1%) on 3’s. Brown had 18 points on 7 of 13 from the field and 3 of 6 on 3’s, while the rest of the team made 7 of 29 shots and only 1 of 13 3’s.

Brown fouled out with 2:50 remaining in the third quarter. A minute later, with the Celtics trailing 92-51, Boston coach Joe Mazzulla called timeout and benched three of his starters (Jrue Holiday, Derrick White and Al Horford) for the rest of the game. Celtics forward Luke Kornet, who made his first career playoff start, sat out the game’s final 8 minutes and 22 seconds.

Brown led the Celtics with 20 points on 8 of 20 shooting, but he was held to two points on 1 of 7 field goals in the second half. Payton Pritchard (11 points) and Horford (10) were the only other Boston players in double figures. The Celtics made just 31 of their 86 shots (36%), which was their worst percentage of the season and a major reason the reigning NBA champion’s season is over.

“Things didn’t go our way this year,” Brown said. “It’s unfortunate, but we hold our heads up regardless. Losing to the Knicks feels like death, but I was always taught that there’s life after death, so we’ll get ready for whatever’s next. Whatever’s next in the journey, I’ll be ready for.”

For the Knicks, what’s next is a return to the court Wednesday night in front of a home crowd that is certain to be loud and proud. For the first time in 25 years, the franchise will be among the final four teams left playing, and it’s appropriate they will be facing the Pacers. From the 1992-93 through 1999-2000 seasons, the Knicks and Pacers played six times in the playoffs in eight seasons. Each team won three series.

The current players are too young to remember those days, although Brunson’s father, Rick, was a reserve for the Knicks in the 1999 and 2000 playoffs. A quarter century later, MSG is rocking again.

“You definitely felt the energy,” Jalen Brunson said. “The way they’ve been supporting us all year, it’s been remarkable. I’m just really happy that we were able to do that.”