Not much seems unusual about Judian and Kadeian Brown’s storefront in a tidy plaza off Church Avenue in Flatbush, Brooklyn, a neighborhood where every block seems to have its own African hair-braiding salon.

Posters of African-American women with long, sleek hair fill the window. Round jars of shea butter belly up to slender boxes of hair dye on the shelves. Wigs perch on mannequin heads.

What makes Black Girls Divine Beauty Supply and Salon’s visitors do a double-take is the skin color of the proprietors. “I go, ‘Look at all the faces on the boxes,’ ” said Judian Brown, recalling other shopkeepers’ and customers’ surprise when they realize she is not an employee, but the owner. “Who should be owning these stores?”

The Brown sisters’ is one small shop in a multibillion-dollar industry, centered on something that is both a point of pride and a political flash point for black women: their hair. But the Browns are among only a few hundred black owners of the roughly 10,000 stores that sell hair products like relaxers, curl creams, wigs and hair weaves to black women, not just in New York but across the country. The vast majority have Korean-American owners, a phenomenon dating back to the 1970s that has stoked tensions between black consumers and Korean businesspeople over what some black people see as one ethnic group profiting from, yet shutting out, another.

A growing awareness of this imbalance has spurred more black people to hang out their own shingles. The people producing the products have changed, too: As “going natural” — abandoning artificially smoothed hair in favor of naturally textured curls and braids — has become more popular and the Internet has expanded, black entrepreneurs, most of them women, are claiming a bigger share of the shelves in women’s medicine cabinets.

“We’re aware of where our dollars are going, we’re aware of the power of our dollars, we’re aware of the cultural significance of the way that we choose to wear our hair,” said Patrice Grell Yursik, the founder of Afrobella, a popular natural-hair blog. “There’s been a lot of taking back the power, and a lot of that is from the Internet.”

Dozens of bloggers flock to industry shows to test new products, review them for their readers and spread the word on social media. Hundreds of thousands of women watch natural hairstyle tutorials on YouTube. Rochelle Graham-Campbell’s line, Alikay Naturals, which she has marketed through her YouTube videos, is among the most successful of the homegrown brands, including Curls and Oyin Handmade, that have gained traction online and earned a spot on retail shelves.

Still, nothing beats brick-and-mortar stores for convenience, and the chance to touch and sniff the creams, which has prompted groups like the Beauty Supply Institute, in Atlanta, to start training blacks to open their own stores.

The ownership question has been fraught for years. Some black customers complain that Korean managers follow them around their stores as if suspecting they will steal. Some black shopkeepers accuse wholesalers and wig manufacturers, most of which are owned by Koreans, of refusing to do business with anyone but other Koreans.

A 2006 documentary about Koreans’ dominance of the industry by Aron Ranen spurred some black women to join boycotts of Korean-owned stores. Mr. Ranen has chronicled one case in Pittsburg, Calif., in which a black store owner was accused of setting fire to a nearby Korean-owned store.

Korean immigrants began entering the American hair business in the 1960s, when wigs were among South Korea’s top exports. Hair-care retail was not much of a leap.

And competition was scant: Until midcentury, many black women bought products from door-to-door saleswomen. Few stores were devoted to hair products. White flight closed many white-owned storefronts, clearing the way for Korean shops.

“A lot of people think these people were taking it away from black owners, but that’s not the case,” said Lori Tharps, a co-author of the book “Hair Story: Untangling the Roots of Black Hair in America.”

“They were creating new businesses,” she said. “And they were doing it in places where nobody else wanted to open a store.”

A saying among Korean immigrants has it that “whoever picks you up at the airport is the one who will give you a job,” whether in beauty supplies or in other Korean-dominated businesses like greengroceries or nail salons.

That proved true for Tony Park, 45, who owns Sugar Beauty Supply on Flatbush Avenue in Prospect-Lefferts Gardens, Brooklyn. Like many other Korean shopkeepers, he got his start in the industry working for a friend’s store after moving to the United States. He saved up to open his own store around four years ago: The American dream, Mr. Park called it.

He explained the Korean connection to the industry simply: “Most wholesalers are Korean. They can speak Korean; I can speak Korean.” (As labor costs rose in South Korea, wig production moved to China and settled more recently elsewhere in Asia, where labor is cheap. Koreans still own many manufacturers.)

Kaysong Lee, the publisher of Beauty Times, an industry publication written in both Korean and English, said he was shocked by the simmering anger directed at Korean owners, many of whom turned to the business after they were shut out of traditional career paths because of the language barrier. He argued in a Beauty Times column in March that the competition between Korean-run stores had driven down prices for black consumers.

“Despite many challenges, Korean-Americans opened their businesses in the heart of African-American communities and made available quality beauty-related products at low prices,” he wrote. “It does not make any sense to treat these hardworking Korean-American business owners as a band of criminals.”

Black people running their own stores say that securing accounts with the major Korean wholesalers can be tough, because they require retailers to buy in bulk to qualify for discounts. For first-time Korean owners, who can join forces with established owners or split costs with other retailers, the way is often smoother, not the least because the wholesalers sometimes offer easier terms to other Koreans.

Outside Detroit, Princess Hill is opening her second beauty supply store catering to black women in an area where black-owned businesses like hers are scarce, part of what she calls a movement to “take the power back from people who made you powerless.”

She found that she would have to order 10,000 berets to qualify for a 50 percent discount and free shipping — an impossible deal, given that she might sell 100 berets in a year.

As a result, she said, customers may complain that “our products can be a quarter more, or even 50 cents or a dollar, than the Korean stores, and they don’t really understand why.” Other black proprietors face complaints about not stocking enough products.

But younger, natural-haired black consumers — “naturalistas,” as some call them — are more aware than ever of where their dollars go, and what goes in their hair.

They are women like Corinthia Alvarez, 25, a nursing student in Brooklyn, who spends up to a few hours a day scrolling through Instagram, watching YouTube videos and reading reviews to learn about new products and styles, and then trying them herself. Her hair can cost her as much as $80 a month.

“You have your phone bill, you have your cable bill and then you have to buy your hair products,” she said on a recent afternoon outside the Hair Shop on Fulton Street in Downtown Brooklyn, where mannequin faces peered alluringly from behind their curtains of false hair in a dozen styles and colors. “Melah” wore a swoop of blond-streaked strands, “Jessy” a coppery-red bob; platinum-blond ringlets cascaded down “Yara’s” shoulders.

Ms. Alvarez’s newest acquisition: Curls “crème brule” whipped curl cream. “I take a lot of pride in my hair,” she said. “If my hair doesn’t look nice, I don’t feel like I’m pretty.”

In South Florida, Ms. Graham-Campbell of Alikay Naturals recently made the biggest announcement of her career to her nearly 100,000 YouTube subscribers: Her line of organic hair creams, oils and conditioners for black women, products she had cooked up in her kitchen, was hitting the shelves of Target stores.

Ms. Graham-Campbell, 27, started her business with $100 as a college student, marketing her products on YouTube and selling them on Etsy. Now her videos can draw as many as 200,000 views from fans. “They want to know, who’s the face behind the brand?” she said. “Are you able to relate to my hair, are you able to relate to my struggles and to my journey of being natural?”

Most of all, she said, she loves hearing from women who notice her photo on Alikay bottles. They tell her that they tell their children: “Someone that looks like you makes that product.”