The feel-good videos of South Korean and Mexican soccer fans dancing and celebrating together in the opening days of the World Cup may have been surprising in many parts of the world, but for the people of Los Angeles, it was nothing new.

The Mexican and Korean communities are an integral part of the city’s vibrant multicultural identity, and their mutual admiration was on show at a watch party in the Koreatown neighborhood on Thursday for the Mexico-South Korea match.

Thousands of people in South Korea and Mexico jerseys packed Seoul International Park, jockeying for the best views of the big screens set up for the match. Many of them were waving South Korean flags while wearing Mexico jerseys. Some South Korea fans had draped themselves in the flags of both countries.

Otilia Barajas, 28, sought shade under a tree a couple of hours before kickoff. She was wearing a special top that she had made herself: One half was a red South Korean jersey, the other was the green of Mexico. Ms. Barajas, who is Mexican American, wore green, white and red eye shadow to represent Mexico, but was torn about cheering for one team over the other.

“I hope they will tie this game,” she said.

Other fans were more competitive.

Austin Hwang, 18, was rooting for a South Korean victory, but was glad to see the melding of red and green in Koreatown.

“It’s quite similar, the vibes that are in Mexico and the vibes that are here,” Mr. Hwang said, referring to the photos and videos of Mexicans and South Koreans partying together in Mexico.

The two fan bases have been seen drinking together, dancing and, in some cases, smooching. The seeds of this soccer love affair were planted during the 2018 World Cup, when South Korea beat Germany and helped Mexico advance to the knockout stage. Videos of Mexico fans thanking South Korea fans after that match went viral.

“In Mexico, they’re welcoming the Koreans with open arms and I feel like all Koreans really appreciate that,” Mr. Hwang said. “Us here, we’re in Koreatown and we can welcome each other. I feel like L.A. is a shared space between the both of us.”

For those who grew up in Los Angeles, the kinship on display on Thursday made sense. Koreatown is home to many people of both Mexican and Korean descent, and considered by many to be one of the few places in the United States where a person can dine on bulgogi tacos or find a taco truck parked in front of a Korean barbecue restaurant.

Jeanwon Kim, 28, was visiting from New York, but grew up in Los Angeles. She wore red with her two friends as they pitched out a blanket on the grass to root for South Korea.

“I feel like the Korean American community and the Mexican American community have always been pretty tight,” Ms. Kim said.

“Seeing the camaraderie in Mexico with Koreans in Mexico, but also seeing the camaraderie in L.A. right now, it’s just such an obvious thing for me.”