KHARTOUM, Sudan — This weekend marked the one-month anniversary of nationwide protests in Sudan that are the most significant challenge yet to President Omar Hassan al-Bashir’s 30 years of authoritarian rule.

The throngs of demonstrators — most in their teens and 20s — have been met with tear gas and bullets. Thousands have been swept up in mass arrests, and at least 40 have been killed, according to human rights groups.

Nearly every day, chanting protesters have crowded the streets of Sudan’s cities, including Sunday, when thousands turned out to demonstrate. They denounce Bashir’s alleged corruption, crimes against humanity and disastrous economic management that has focused on military spending while continuing to raise the prices of basic goods such as flour.

But interspersed among the ­anti-Bashir chants that have become the soundtrack of this uprising is a bitter phrase that underlines the unprecedented power of these protests: “Oh, you arrogant racist, we are all Darfur.”

After decades of successfully exploiting Sudan’s racial divides between ethnic Arabs who live along the Nile River and ethnic Africans in Sudan’s Darfur region, a new generation is fed up and is hoping ethnic solidarity against Bashir will lead to his downfall.

“It just does not work anymore,” said Osman Ahmad, one of the young protesters on the streets of the capital, Khartoum. “They may have successfully divided us in the past, and it worked on our parents and grandparents. But it’s not working on us, the new generation. We are on to them.”

Bashir’s reign has been punctuated by brutal crackdowns against perceived uprisings in the country’s west and south, areas where darker-skinned Sudanese people are a majority. In the early 2000s, he recruited ethnic Arab militias known as the Janjaweed to Darfur, where they committed mass killings and rape and drove the entire region into hiding and hunger. Bashir remains under indictment for war crimes by the International Criminal Court, and some allege he directed a genocide in Darfur.

In 2011, Bashir also conceded in a long and bloody civil war with Sudan’s southernmost regions, resulting in their secession and the creation of South Sudan.

He has attempted to pin the ongoing protests on students from Darfur and said they set fire to an office of his ruling National Congress Party in mid-December.

Nasredeen Abdulbari, a researcher from Darfur at Georgetown University in Washington, called Bashir’s claim an “obvious lie” and said most Sudanese knew that the protests had “nothing to do with Darfur” and were instead provoked by people’s frustration over their inability to find affordable wheat flour to make bread.

The effort to use Darfur as a scapegoat backfired, and Bashir’s perceived racism and divisive tactics have become a rallying cry against him.

Sudan’s median age is 19 — half of what it is in the United States. That means the vast majority of Sudanese people have known only Bashir’s rule and the culture of fear he has inculcated by meeting past protests with deadly violence.

But heavy-handed tactics haven’t appeared to work this time. The protests have grown and spread to every region of the country, including Darfur, where crackdowns have been the most brutal in the past.

“It seems the millennials, who are leading the protests, just like their counterparts in other places in the world, think beyond the regional and ethnic dichotomies of their society,” Abdulbari said, adding that the “we are one” message has infused the protests and the country with hope for a less fractured future after Bashir.

Sudan’s fledgling opposition has tried to take advantage of the solidarity among the protesters.

“The attempt of the regime to use the weapon of ethnic polarization has produced the opposite effect, which is a sense of national solidarity and common desire for change,” said Khalid Omar, the secretary general of the opposition Sudanese Congress Party, in an interview with The Washington Post.

Bashir remains defiant. In speeches in front of his supporters, he describes the protesters as saboteurs. He has pledged not to step down until elections in 2020.

His government has tightened censorship of the country’s broadcast and print media, arresting journalists and confiscating newspapers with coverage of the protests. Access to social media such as Facebook, Twitter, Instagram and WhatsApp has been blocked, though many people have downloaded virtual private networks, or VPNs, to circumvent the blackout.

A government assault last week on a hospital in Omdurman, across the Nile from Khartoum, drew international condemnation, though the situation in Sudan has failed to capture the world’s attention the way the Arab Spring protests did in the early 2010s. Security forces entered the hospital and shot tear gas and bullets at doctors, some of whom were treating people who had been injured in protests that day.

Two protesters were killed Thursday by security forces, according to the Sudanese Professionals Association, which has taken charge of organizing the protests. On Friday, protesters marched toward the presidential palace in Khartoum, chanting, “We are not scared, we will not stop! . . . Freedom, peace, justice!”

The protesters see not just a chance to get rid of Bashir, but also a chance to reimagine Sudanese society.

“We want a country free of racism,” said Khalid Siddiq, a protester in Khartoum. “We can no longer afford to be massacred everywhere in this country and remain silent.”