In the summer of 1989, Tim Walz faced a difficult choice.

A newly minted college graduate from small-town Nebraska, he had just turned down a stable, 9-to-5 job offer and moved across the world to teach at a local high school in China. He had made it as far as Hong Kong, just across the Chinese border, when People’s Liberation Army tanks rolled into Tiananmen Square to crush pro-democracy protests.

Rumors were flying about a possible civil war in China. Many foreigners, including most American teachers, had fled the country. Should he go back home or continue his journey into China?

He decided to go in.

“It was my belief at that time that the diplomacy was going to happen on many levels, certainly people to people,” Mr. Walz recalled in 2014 during a congressional hearing marking the 25th anniversary of the Tiananmen Square crackdown. “The opportunity to be in a Chinese high school at that critical time seemed to me to be really important.”

The one year that Mr. Walz spent teaching English in southern China was the start of what would become a decades-long relationship with the country. As high school teachers in Nebraska and Minnesota, Mr. Walz and his wife, Gwen, regularly led trips to China in the 1990s and early 2000s to introduce students to China’s history and culture. Mr. Walz has said that he has traveled to China some 30 times, including for his honeymoon.

That deep history of engagement with China reflects a lesser-known international dimension of the Democratic vice-presidential candidate. If elected vice president, Mr. Walz would bring to the White House unusually extensive personal experience in China — a history that supporters say could be an asset at a time of volatile relations between Washington and Beijing.

But the campaign has so far made little mention of Mr. Walz’s experience there, even as it has leaned into depictions of the Minnesota governor as an avuncular Midwestern dad, coach and teacher. And it has yet to lay out how Vice President Kamala Harris or Mr. Walz would handle China, which both the Biden and Trump administrations have treated with toughness.