The buzzword at the best soccer clubs in Europe these days is global, as in global brand or global footprint or global reach. Bayern Munich wants to be known in Asia and Australia. Barcelona wants to be known in the Middle East. Everyone wants to be known in Africa and the United States.

Here though, in the Basque country of northern Spain, there is a club — a team with eight Spanish league titles, 23 domestic cup titles, frequent appearances in the continental competitions and the distinction of never having been relegated from the first division — with comparatively little interest in getting bigger.

It is not that executives at Athletic Club (or, as it is often called by outsiders, Athletic Bilbao) do not seek popularity, or success. It is just that the primary reasons that megaclubs are chasing new frontiers — to acquire more money to spend on ever more expensive players and more access to young talents — do not apply here.

While teams like Manchester United and Real Madrid and Paris St.-Germain scour the globe for players and pay millions to import the game’s biggest stars, Athletic’s player policy has been — for more than a century — remarkably simple: If you are not from here, you cannot play here.

At Athletic, there are no prospects plucked from obscure Brazilian villages. No wunderkind strikers bought for a bounty. No grizzled veterans signed from down south or just across the border with France.

When Athletic played Partizan Belgrade in a Europa League match here Thursday night, eight of its starting 11 players had risen through the club’s academy. The other three have Basque heritage.

This is by design. Despite its place in one of the biggest leagues in the world, Athletic is, at its core, a local club.

“For us, the rest of the teams — with all respect — they seem like photocopies,” said Josu Urrutia, a former player for Athletic and its current president. “Better or worse players, OK, but with the same idea.

“In our case, it’s a small-town way of thinking,” he continued. “If we can get people to represent the town and its surroundings, this is the ultimate. It’s not representing an international team; it’s representing us.”

The Basques-only policy is not written anywhere in the club’s bylaws, so it is not an official rule. If Athletic’s leaders wanted to follow the path of their neighbors at Real Sociedad, which had a similar policy until 1989 (when it was abandoned for competitive reasons), there is nothing stopping them.

Yet Athletic is one of three clubs in Spain that are owned by its members, which means, among other things, that the members elect the president. And Urrutia said that in the club’s history, there had never been a presidential candidate who tried to run on a campaign that included a promise to alter Athletic’s policy, nor any sizable contingent of officials or fans eager to even discuss changing it.

“In Basque country, we have five teams playing top professional football and we have 3 million people,” said José Maria Amorrortu, Athletic’s sporting director. “Many people ask, ‘How is it possible?’ And you know there are some things that you cannot explain that exist. And I think this is one of them.”

Athletic is not the only club in the world to have such a self-restricting policy — Chivas, in Mexico, historically signed only Mexican nationals, though that rule was relaxed slightly in recent years — but it is unquestionably the highest-profile team to do so. Keeping the policy in place, its fans believe, has become enmeshed with preserving the Basque identity.

The Basque country was recognized as an autonomous region within Spain in 1978, though Athletic’s definition for player eligibility purposes also includes the outskirts of the traditional Basque region, allowing a player such as the defender Aymeric Laporte, who is from Aquitane in southern France, to play.

Heritage has always been part of Athletic’s fabric: The team’s primary jersey has vertical red and white stripes, showing two of the three Basque colors (green is the third); Basque berets can be found for sale (and on heads) around the redesigned Estadio de San Mamés; and coaches at Athletic’s academy frequently instruct the players in Basque instead of Spanish.

Before Thursday’s match, the stadium announcer listed the starting players in Basque, and when Athletic and Barcelona — the flagship team of another autonomous community, Catalonia — played in the Copa del Rey final this year, both teams were penalized because their fans whistled during the playing of the Spanish national anthem.

“We have our own language, culture, music, sports and everything that makes a country different from another,” Imanol Amuriza Saratxaga, 32, a fan of Athletic, said Thursday.

Fans and club officials are aware of the drawbacks and criticisms of their policy. From a business standpoint, it clearly limits the club strategically; Athletic is essentially reducing its player pool to a population roughly similar to that of Connecticut. And from a social and cultural perspective, there are some who find the policy to be exclusionary, even offensive. In a time of increased migration and cross-border movement in Europe and elsewhere, is it appropriate to reject anyone out of hand?

Urrutia, the club president, said the policy had the flexibility to grow with the times. For example, he said, immigrants or refugees who come to Bilbao with young children, or who later have children, can enroll them in Athletic’s academy. Race is not a restriction either, Urrutia said: Iñaki Williams, whose mother is Ghanaian and whose father is Liberian, was born in Bilbao, plays for Athletic and scored two goals on Thursday.

Anyone, even the child of an American expatriate in Bilbao, can play for Athletic, Urrutia said, as long as the person grows up as part of the Basque community. It is that sense of identity — of belonging to the group — that is the root of the policy more than animus against anyone else.

Amorrortu, the sporting director, said he believed that a child needed to be part of the academy by age 14 or 15, at the latest, to truly absorb Athletic’s identity. Having so many players come through the academy feeds the club’s link to the wider Basque community, too, which is why matches for Athletic’s youth teams or reserve team can draw crowds of 10,000 or more.

The policy “makes the people feel part of the team,” said Amuriza, the fan, “because you always know someone close to one or more of the players, and every child in the Basque country knows they can one day play in San Mamés.

This season, Athletic has continued its solid play, currently sitting in eighth place in La Liga and atop its group in the Europa League after its 5-1 victory over Partizan. The last time Athletic was in danger of relegation to Spain’s second division was 2007 (it finished just one spot above the drop line), but Urrutia said he was sure there would be another season when the club struggled and outsiders wondered if Athletic would consider a change to its player policy.

To those within the club, however, such talk is anathema.

“Why do we love our children more than anyone else?” Urrutia said. “Because they are our children, of course. We do this for them, to keep their identity always.”

He smiled. “We think of it like this: Anyone can win or lose. We want to win or lose our way.”